diff --git a/launcher/InstanceList.cpp b/launcher/InstanceList.cpp
index 6b0e3a4b..cebd70d7 100644
--- a/launcher/InstanceList.cpp
+++ b/launcher/InstanceList.cpp
@@ -535,7 +535,7 @@ InstancePtr InstanceList::getInstanceById(QString instId) const
     return InstancePtr();
 }
 
-InstancePtr InstanceList::getInstanceByManagedName(QString managed_name) const
+InstancePtr InstanceList::getInstanceByManagedName(const QString& managed_name) const
 {
     if (managed_name.isEmpty())
         return {};
@@ -880,7 +880,7 @@ QString InstanceList::getStagedInstancePath()
     return path;
 }
 
-bool InstanceList::commitStagedInstance(QString path, InstanceName const& instanceName, QString groupName, bool should_override)
+bool InstanceList::commitStagedInstance(const QString& path, InstanceName const& instanceName, const QString& groupName, bool should_override)
 {
     QDir dir;
     QString instID;
diff --git a/launcher/InstanceList.h b/launcher/InstanceList.h
index df11b55a..3673298f 100644
--- a/launcher/InstanceList.h
+++ b/launcher/InstanceList.h
@@ -104,7 +104,7 @@ public:
     /* O(n) */
     InstancePtr getInstanceById(QString id) const;
     /* O(n) */
-    InstancePtr getInstanceByManagedName(QString managed_name) const;
+    InstancePtr getInstanceByManagedName(const QString& managed_name) const;
     QModelIndex getInstanceIndexById(const QString &id) const;
     QStringList getGroups();
     bool isGroupCollapsed(const QString &groupName);
@@ -133,7 +133,7 @@ public:
      * should_override is used when another similar instance already exists, and we want to override it
      * - for instance, when updating it.
      */
-    bool commitStagedInstance(QString keyPath, const InstanceName& instanceName, QString groupName, bool should_override);
+    bool commitStagedInstance(const QString& keyPath, const InstanceName& instanceName, const QString& groupName, bool should_override);
 
     /**
      * Destroy a previously created staging area given by @keyPath - used when creation fails.
diff --git a/launcher/InstanceTask.cpp b/launcher/InstanceTask.cpp
index da280731..55a44fd3 100644
--- a/launcher/InstanceTask.cpp
+++ b/launcher/InstanceTask.cpp
@@ -2,7 +2,7 @@
 
 #include "ui/dialogs/CustomMessageBox.h"
 
-InstanceNameChange askForChangingInstanceName(QWidget* parent, QString old_name, QString new_name)
+InstanceNameChange askForChangingInstanceName(QWidget* parent, const QString& old_name, const QString& new_name)
 {
     auto dialog =
         CustomMessageBox::selectable(parent, QObject::tr("Change instance name"),
diff --git a/launcher/InstanceTask.h b/launcher/InstanceTask.h
index 0987b557..e35533fc 100644
--- a/launcher/InstanceTask.h
+++ b/launcher/InstanceTask.h
@@ -5,7 +5,7 @@
 
 /* Helpers */
 enum class InstanceNameChange { ShouldChange, ShouldKeep };
-[[nodiscard]] InstanceNameChange askForChangingInstanceName(QWidget* parent, QString old_name, QString new_name);
+[[nodiscard]] InstanceNameChange askForChangingInstanceName(QWidget* parent, const QString& old_name, const QString& new_name);
 
 struct InstanceName {
    public:
diff --git a/launcher/minecraft/VanillaInstanceCreationTask.cpp b/launcher/minecraft/VanillaInstanceCreationTask.cpp
index fb11379c..c45daa9a 100644
--- a/launcher/minecraft/VanillaInstanceCreationTask.cpp
+++ b/launcher/minecraft/VanillaInstanceCreationTask.cpp
@@ -1,12 +1,14 @@
 #include "VanillaInstanceCreationTask.h"
 
+#include <utility>
+
 #include "FileSystem.h"
 #include "minecraft/MinecraftInstance.h"
 #include "minecraft/PackProfile.h"
 #include "settings/INISettingsObject.h"
 
 VanillaCreationTask::VanillaCreationTask(BaseVersionPtr version, QString loader, BaseVersionPtr loader_version)
-    : InstanceCreationTask(), m_version(version), m_using_loader(true), m_loader(loader), m_loader_version(loader_version)
+    : InstanceCreationTask(), m_version(std::move(version)), m_using_loader(true), m_loader(std::move(loader)), m_loader_version(std::move(loader_version))
 {}
 
 bool VanillaCreationTask::createInstance()
diff --git a/launcher/minecraft/VanillaInstanceCreationTask.h b/launcher/minecraft/VanillaInstanceCreationTask.h
index 540ecb70..7a37bbd6 100644
--- a/launcher/minecraft/VanillaInstanceCreationTask.h
+++ b/launcher/minecraft/VanillaInstanceCreationTask.h
@@ -2,10 +2,12 @@
 
 #include "InstanceCreationTask.h"
 
+#include <utility>
+
 class VanillaCreationTask final : public InstanceCreationTask {
     Q_OBJECT
    public:
-    VanillaCreationTask(BaseVersionPtr version) : InstanceCreationTask(), m_version(version) {}
+    VanillaCreationTask(BaseVersionPtr version) : InstanceCreationTask(), m_version(std::move(version)) {}
     VanillaCreationTask(BaseVersionPtr version, QString loader, BaseVersionPtr loader_version);
 
     bool createInstance() override;
diff --git a/launcher/modplatform/flame/FlameAPI.cpp b/launcher/modplatform/flame/FlameAPI.cpp
index f8f50dc6..4d71da21 100644
--- a/launcher/modplatform/flame/FlameAPI.cpp
+++ b/launcher/modplatform/flame/FlameAPI.cpp
@@ -184,7 +184,7 @@ auto FlameAPI::getProjects(QStringList addonIds, QByteArray* response) const ->
     return netJob;
 }
 
-auto FlameAPI::getFiles(QStringList fileIds, QByteArray* response) const -> NetJob*
+auto FlameAPI::getFiles(const QStringList& fileIds, QByteArray* response) const -> NetJob*
 {
     auto* netJob = new NetJob(QString("Flame::GetFiles"), APPLICATION->network());
 
diff --git a/launcher/modplatform/flame/FlameAPI.h b/launcher/modplatform/flame/FlameAPI.h
index 5e6166b9..4c6ca64c 100644
--- a/launcher/modplatform/flame/FlameAPI.h
+++ b/launcher/modplatform/flame/FlameAPI.h
@@ -12,7 +12,7 @@ class FlameAPI : public NetworkModAPI {
     auto getLatestVersion(VersionSearchArgs&& args) -> ModPlatform::IndexedVersion;
 
     auto getProjects(QStringList addonIds, QByteArray* response) const -> NetJob* override;
-    auto getFiles(QStringList fileIds, QByteArray* response) const -> NetJob*;
+    auto getFiles(const QStringList& fileIds, QByteArray* response) const -> NetJob*;
 
    private:
     inline auto getSortFieldInt(QString sortString) const -> int
diff --git a/launcher/modplatform/flame/FlameInstanceCreationTask.cpp b/launcher/modplatform/flame/FlameInstanceCreationTask.cpp
index 69a41e55..48ac02e0 100644
--- a/launcher/modplatform/flame/FlameInstanceCreationTask.cpp
+++ b/launcher/modplatform/flame/FlameInstanceCreationTask.cpp
@@ -126,7 +126,7 @@ bool FlameCreationTask::updateInstance()
         // TODO: Currently 'overrides' will always override the stuff on update. How do we preserve unchanged overrides?
         // FIXME: We may want to do something about disabled mods.
         auto old_overrides = Override::readOverrides("overrides", old_index_folder);
-        for (auto entry : old_overrides) {
+        for (const auto& entry : old_overrides) {
             if (entry.isEmpty())
                 continue;
             qDebug() << "Scheduling" << entry << "for removal";
@@ -320,7 +320,7 @@ bool FlameCreationTask::createInstance()
         qDebug() << "Found jarmods:";
         QDir jarmodsDir(jarmodsPath);
         QStringList jarMods;
-        for (auto info : jarmodsDir.entryInfoList(QDir::NoDotAndDotDot | QDir::Files)) {
+        for (const auto& info : jarmodsDir.entryInfoList(QDir::NoDotAndDotDot | QDir::Files)) {
             qDebug() << info.fileName();
             jarMods.push_back(info.absoluteFilePath());
         }
diff --git a/launcher/modplatform/flame/FlameInstanceCreationTask.h b/launcher/modplatform/flame/FlameInstanceCreationTask.h
index ccb5f827..ded0e2ce 100644
--- a/launcher/modplatform/flame/FlameInstanceCreationTask.h
+++ b/launcher/modplatform/flame/FlameInstanceCreationTask.h
@@ -14,7 +14,7 @@ class FlameCreationTask final : public InstanceCreationTask {
     Q_OBJECT
 
    public:
-    FlameCreationTask(QString staging_path, SettingsObjectPtr global_settings, QWidget* parent)
+    FlameCreationTask(const QString& staging_path, SettingsObjectPtr global_settings, QWidget* parent)
         : InstanceCreationTask(), m_parent(parent)
     {
         setStagingPath(staging_path);
diff --git a/launcher/modplatform/helpers/OverrideUtils.cpp b/launcher/modplatform/helpers/OverrideUtils.cpp
index 3496a286..65b5f760 100644
--- a/launcher/modplatform/helpers/OverrideUtils.cpp
+++ b/launcher/modplatform/helpers/OverrideUtils.cpp
@@ -6,7 +6,7 @@
 
 namespace Override {
 
-void createOverrides(QString name, QString parent_folder, QString override_path)
+void createOverrides(const QString& name, const QString& parent_folder, const QString& override_path)
 {
     QString file_path(FS::PathCombine(parent_folder, name + ".txt"));
     if (QFile::exists(file_path))
@@ -33,7 +33,7 @@ void createOverrides(QString name, QString parent_folder, QString override_path)
     file.close();
 }
 
-QStringList readOverrides(QString name, QString parent_folder)
+QStringList readOverrides(const QString& name, const QString& parent_folder)
 {
     QString file_path(FS::PathCombine(parent_folder, name + ".txt"));
 
diff --git a/launcher/modplatform/helpers/OverrideUtils.h b/launcher/modplatform/helpers/OverrideUtils.h
index 73f059d6..536261a2 100644
--- a/launcher/modplatform/helpers/OverrideUtils.h
+++ b/launcher/modplatform/helpers/OverrideUtils.h
@@ -9,12 +9,12 @@ namespace Override {
  *
  *  If there's already an existing such file, it will be ovewritten.
  */
-void createOverrides(QString name, QString parent_folder, QString override_path);
+void createOverrides(const QString& name, const QString& parent_folder, const QString& override_path);
 
 /** This reads an existing overrides archive, returning a list of overrides.
  *
  *  If there's no such file in `parent_folder`, it will return an empty list.
  */
-QStringList readOverrides(QString name, QString parent_folder);
+QStringList readOverrides(const QString& name, const QString& parent_folder);
 
 }  // namespace Override
diff --git a/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp b/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp
index 2cb6e786..f9709551 100644
--- a/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp
+++ b/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp
@@ -121,7 +121,7 @@ bool ModrinthCreationTask::updateInstance()
         // TODO: Currently 'overrides' will always override the stuff on update. How do we preserve unchanged overrides?
         // FIXME: We may want to do something about disabled mods.
         auto old_overrides = Override::readOverrides("overrides", old_index_folder);
-        for (auto entry : old_overrides) {
+        for (const auto& entry : old_overrides) {
             if (entry.isEmpty())
                 continue;
             qDebug() << "Scheduling" << entry << "for removal";
@@ -129,7 +129,7 @@ bool ModrinthCreationTask::updateInstance()
         }
 
         auto old_client_overrides = Override::readOverrides("client-overrides", old_index_folder);
-        for (auto entry : old_overrides) {
+        for (const auto& entry : old_overrides) {
             if (entry.isEmpty())
                 continue;
             qDebug() << "Scheduling" << entry << "for removal";
@@ -235,7 +235,7 @@ bool ModrinthCreationTask::createInstance()
         dl->addValidator(new Net::ChecksumValidator(file.hashAlgorithm, file.hash));
         m_files_job->addNetAction(dl);
 
-        if (file.downloads.size() > 0) {
+        if (!file.downloads.empty()) {
             // FIXME: This really needs to be put into a ConcurrentTask of
             // MultipleOptionsTask's , once those exist :)
             connect(dl.get(), &NetAction::failed, [this, &file, path, dl] {
@@ -281,7 +281,7 @@ bool ModrinthCreationTask::createInstance()
     return ended_well;
 }
 
-bool ModrinthCreationTask::parseManifest(QString index_path, std::vector<Modrinth::File>& files, bool set_managed_info, bool show_optional_dialog)
+bool ModrinthCreationTask::parseManifest(const QString& index_path, std::vector<Modrinth::File>& files, bool set_managed_info, bool show_optional_dialog)
 {
     try {
         auto doc = Json::requireDocument(index_path);
@@ -300,7 +300,7 @@ bool ModrinthCreationTask::parseManifest(QString index_path, std::vector<Modrint
 
             auto jsonFiles = Json::requireIsArrayOf<QJsonObject>(obj, "files", "modrinth.index.json");
             bool had_optional = false;
-            for (auto modInfo : jsonFiles) {
+            for (const auto& modInfo : jsonFiles) {
                 Modrinth::File file;
                 file.path = Json::requireString(modInfo, "path");
 
diff --git a/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.h b/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.h
index 01d0d1bf..e459aadf 100644
--- a/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.h
+++ b/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.h
@@ -27,7 +27,7 @@ class ModrinthCreationTask final : public InstanceCreationTask {
     bool createInstance() override;
 
    private:
-    bool parseManifest(QString, std::vector<Modrinth::File>&, bool set_managed_info = true, bool show_optional_dialog = true);
+    bool parseManifest(const QString&, std::vector<Modrinth::File>&, bool set_managed_info = true, bool show_optional_dialog = true);
     QString getManagedPackID() const;
 
    private:
diff --git a/launcher/ui/dialogs/NewInstanceDialog.cpp b/launcher/ui/dialogs/NewInstanceDialog.cpp
index 04fecbde..d203795a 100644
--- a/launcher/ui/dialogs/NewInstanceDialog.cpp
+++ b/launcher/ui/dialogs/NewInstanceDialog.cpp
@@ -51,6 +51,7 @@
 #include <QFileDialog>
 #include <QValidator>
 #include <QDialogButtonBox>
+#include <utility>
 
 #include "ui/widgets/PageContainer.h"
 #include "ui/pages/modplatform/VanillaPage.h"
@@ -177,7 +178,7 @@ NewInstanceDialog::~NewInstanceDialog()
     delete ui;
 }
 
-void NewInstanceDialog::setSuggestedPack(QString name, InstanceTask* task)
+void NewInstanceDialog::setSuggestedPack(const QString& name, InstanceTask* task)
 {
     creationTask.reset(task);
 
@@ -193,12 +194,12 @@ void NewInstanceDialog::setSuggestedPack(QString name, InstanceTask* task)
     m_buttons->button(QDialogButtonBox::Ok)->setEnabled(allowOK);
 }
 
-void NewInstanceDialog::setSuggestedPack(QString name, QString version, InstanceTask* task)
+void NewInstanceDialog::setSuggestedPack(const QString& name, QString version, InstanceTask* task)
 {
     creationTask.reset(task);
 
     ui->instNameTextBox->setPlaceholderText(name);
-    importVersion = version;
+    importVersion = std::move(version);
 
     if (!task) {
         ui->iconButton->setIcon(APPLICATION->icons()->getIcon("default"));
diff --git a/launcher/ui/dialogs/NewInstanceDialog.h b/launcher/ui/dialogs/NewInstanceDialog.h
index 185ab9e6..961f512e 100644
--- a/launcher/ui/dialogs/NewInstanceDialog.h
+++ b/launcher/ui/dialogs/NewInstanceDialog.h
@@ -60,8 +60,8 @@ public:
 
     void updateDialogState();
 
-    void setSuggestedPack(QString name = QString(), InstanceTask * task = nullptr);
-    void setSuggestedPack(QString name, QString version, InstanceTask * task = nullptr);
+    void setSuggestedPack(const QString& name = QString(), InstanceTask * task = nullptr);
+    void setSuggestedPack(const QString& name, QString version, InstanceTask * task = nullptr);
     void setSuggestedIconFromFile(const QString &path, const QString &name);
     void setSuggestedIcon(const QString &key);