diff --git a/core/hw/sh4/dyna/blockmanager.cpp b/core/hw/sh4/dyna/blockmanager.cpp
index fa639094e..47d91af51 100644
--- a/core/hw/sh4/dyna/blockmanager.cpp
+++ b/core/hw/sh4/dyna/blockmanager.cpp
@@ -507,12 +507,12 @@ RuntimeBlockInfo::~RuntimeBlockInfo()
 	}
 }
 
-void RuntimeBlockInfo::AddRef(RuntimeBlockInfoPtr other)
+void RuntimeBlockInfo::AddRef(const RuntimeBlockInfoPtr& other)
 { 
 	pre_refs.push_back(other); 
 }
 
-void RuntimeBlockInfo::RemRef(RuntimeBlockInfoPtr other)
+void RuntimeBlockInfo::RemRef(const RuntimeBlockInfoPtr& other)
 {
 	bm_List::iterator it = std::find(pre_refs.begin(), pre_refs.end(), other);
 	if (it != pre_refs.end())
diff --git a/core/hw/sh4/dyna/blockmanager.h b/core/hw/sh4/dyna/blockmanager.h
index c6d2823c3..b7d1c537f 100644
--- a/core/hw/sh4/dyna/blockmanager.h
+++ b/core/hw/sh4/dyna/blockmanager.h
@@ -68,8 +68,8 @@ struct RuntimeBlockInfo: RuntimeBlockInfo_Core
 	//predecessors references
 	std::vector<RuntimeBlockInfoPtr> pre_refs;
 
-	void AddRef(RuntimeBlockInfoPtr other);
-	void RemRef(RuntimeBlockInfoPtr other);
+	void AddRef(const RuntimeBlockInfoPtr& other);
+	void RemRef(const RuntimeBlockInfoPtr& other);
 
 	void Discard();
 	void SetProtectedFlags();
diff --git a/core/input/gamepad_device.cpp b/core/input/gamepad_device.cpp
index 972c52bc4..6df514507 100644
--- a/core/input/gamepad_device.cpp
+++ b/core/input/gamepad_device.cpp
@@ -406,7 +406,7 @@ static FILE *get_record_input(bool write)
 }
 #endif
 
-void GamepadDevice::Register(std::shared_ptr<GamepadDevice> gamepad)
+void GamepadDevice::Register(const std::shared_ptr<GamepadDevice>& gamepad)
 {
 	int maple_port = cfgLoadInt("input",
 			MAPLE_PORT_CFG_PREFIX + gamepad->unique_id(), 12345);
@@ -425,7 +425,7 @@ void GamepadDevice::Register(std::shared_ptr<GamepadDevice> gamepad)
 	_gamepads_mutex.unlock();
 }
 
-void GamepadDevice::Unregister(std::shared_ptr<GamepadDevice> gamepad)
+void GamepadDevice::Unregister(const std::shared_ptr<GamepadDevice>& gamepad)
 {
 	gamepad->save_mapping();
 	_gamepads_mutex.lock();
diff --git a/core/input/gamepad_device.h b/core/input/gamepad_device.h
index 9ff9b885a..5b225137b 100644
--- a/core/input/gamepad_device.h
+++ b/core/input/gamepad_device.h
@@ -57,9 +57,9 @@ public:
 	virtual void update_rumble() {}
 	bool is_rumble_enabled() { return _rumble_enabled; }
 
-	static void Register(std::shared_ptr<GamepadDevice> gamepad);
+	static void Register(const std::shared_ptr<GamepadDevice>& gamepad);
 
-	static void Unregister(std::shared_ptr<GamepadDevice> gamepad);
+	static void Unregister(const std::shared_ptr<GamepadDevice>& gamepad);
 
 	static int GetGamepadCount();
 	static std::shared_ptr<GamepadDevice> GetGamepad(int index);
diff --git a/core/input/mapping.cpp b/core/input/mapping.cpp
index de37282e2..07bae18e7 100644
--- a/core/input/mapping.cpp
+++ b/core/input/mapping.cpp
@@ -284,7 +284,7 @@ bool InputMapping::save(const char *name)
 	return true;
 }
 
-void InputMapping::SaveMapping(const char *name, std::shared_ptr<InputMapping> mapping)
+void InputMapping::SaveMapping(const char *name, const std::shared_ptr<InputMapping>& mapping)
 {
 	mapping->save(name);
 	InputMapping::loaded_mappings[name] = mapping;
diff --git a/core/input/mapping.h b/core/input/mapping.h
index c68579ab7..95fd773e5 100644
--- a/core/input/mapping.h
+++ b/core/input/mapping.h
@@ -80,7 +80,7 @@ public:
 	bool is_dirty() { return dirty; }
 
 	static std::shared_ptr<InputMapping> LoadMapping(const char *name);
-	static void SaveMapping(const char *name, std::shared_ptr<InputMapping> mapping);
+	static void SaveMapping(const char *name, const std::shared_ptr<InputMapping>& mapping);
 
 protected:
 	bool dirty = false;
diff --git a/core/oslib/directory.h b/core/oslib/directory.h
index 693b95636..d21870fd1 100644
--- a/core/oslib/directory.h
+++ b/core/oslib/directory.h
@@ -137,7 +137,7 @@ public:
 	class iterator
 	{
 	private:
-		iterator(DIR *dir, std::string pathname) {
+		iterator(DIR *dir, const std::string& pathname) {
 			if (dir != nullptr)
 			{
 				dirs.push_back(dir);
diff --git a/core/rend/gui.cpp b/core/rend/gui.cpp
index a9969855c..809370c9d 100644
--- a/core/rend/gui.cpp
+++ b/core/rend/gui.cpp
@@ -634,7 +634,7 @@ static void detect_input_popup(int index, bool analog)
 	ImGui::PopStyleVar(2);
 }
 
-static void controller_mapping_popup(std::shared_ptr<GamepadDevice> gamepad)
+static void controller_mapping_popup(const std::shared_ptr<GamepadDevice>& gamepad)
 {
 	ImGui::SetNextWindowPos(ImVec2(0, 0));
 	ImGui::SetNextWindowSize(ImVec2(screen_width, screen_height));
diff --git a/core/rend/vulkan/buffer.cpp b/core/rend/vulkan/buffer.cpp
index 70e96421d..19acf3b9f 100644
--- a/core/rend/vulkan/buffer.cpp
+++ b/core/rend/vulkan/buffer.cpp
@@ -22,7 +22,7 @@
 #include "utils.h"
 #include "vulkan_context.h"
 
-BufferData::BufferData(vk::DeviceSize size, vk::BufferUsageFlags usage, vk::MemoryPropertyFlags propertyFlags)
+BufferData::BufferData(vk::DeviceSize size, const vk::BufferUsageFlags& usage, const vk::MemoryPropertyFlags& propertyFlags)
 	: bufferSize(size), m_usage(usage), m_propertyFlags(propertyFlags)
 {
 	VulkanContext *context = VulkanContext::Instance();
diff --git a/core/rend/vulkan/buffer.h b/core/rend/vulkan/buffer.h
index f0fbdd5ad..8c3c64dfd 100644
--- a/core/rend/vulkan/buffer.h
+++ b/core/rend/vulkan/buffer.h
@@ -24,8 +24,8 @@
 
 struct BufferData
 {
-	BufferData(vk::DeviceSize size, vk::BufferUsageFlags usage,
-			vk::MemoryPropertyFlags propertyFlags = vk::MemoryPropertyFlagBits::eHostVisible | vk::MemoryPropertyFlagBits::eHostCoherent);
+	BufferData(vk::DeviceSize size, const vk::BufferUsageFlags& usage,
+			const vk::MemoryPropertyFlags& propertyFlags = vk::MemoryPropertyFlagBits::eHostVisible | vk::MemoryPropertyFlagBits::eHostCoherent);
 	~BufferData()
 	{
 		buffer.reset();
diff --git a/core/rend/vulkan/texture.cpp b/core/rend/vulkan/texture.cpp
index 671071a3c..83eb4c5d8 100644
--- a/core/rend/vulkan/texture.cpp
+++ b/core/rend/vulkan/texture.cpp
@@ -226,8 +226,8 @@ void Texture::Init(u32 width, u32 height, vk::Format format, u32 dataSize, bool
 	CreateImage(imageTiling, usageFlags, initialLayout, vk::ImageAspectFlagBits::eColor);
 }
 
-void Texture::CreateImage(vk::ImageTiling tiling, vk::ImageUsageFlags usage, vk::ImageLayout initialLayout,
-		vk::ImageAspectFlags aspectMask)
+void Texture::CreateImage(vk::ImageTiling tiling, const vk::ImageUsageFlags& usage, vk::ImageLayout initialLayout,
+		const vk::ImageAspectFlags& aspectMask)
 {
 	vk::ImageCreateInfo imageCreateInfo(vk::ImageCreateFlags(), vk::ImageType::e2D, format, vk::Extent3D(extent, 1), mipmapLevels, 1,
 										vk::SampleCountFlagBits::e1, tiling, usage,
@@ -393,7 +393,7 @@ void Texture::GenerateMipmaps()
 	commandBuffer.pipelineBarrier(vk::PipelineStageFlagBits::eTransfer, vk::PipelineStageFlagBits::eFragmentShader, {}, nullptr, nullptr, barrier);
 }
 
-void FramebufferAttachment::Init(u32 width, u32 height, vk::Format format, vk::ImageUsageFlags usage)
+void FramebufferAttachment::Init(u32 width, u32 height, vk::Format format, const vk::ImageUsageFlags& usage)
 {
 	this->format = format;
 	this->extent = vk::Extent2D { width, height };
diff --git a/core/rend/vulkan/texture.h b/core/rend/vulkan/texture.h
index b3511d78a..8fc875baa 100644
--- a/core/rend/vulkan/texture.h
+++ b/core/rend/vulkan/texture.h
@@ -51,8 +51,8 @@ public:
 private:
 	void Init(u32 width, u32 height, vk::Format format ,u32 dataSize, bool mipmapped, bool mipmapsIncluded);
 	void SetImage(u32 size, void *data, bool isNew, bool genMipmaps);
-	void CreateImage(vk::ImageTiling tiling, vk::ImageUsageFlags usage, vk::ImageLayout initialLayout,
-			vk::ImageAspectFlags aspectMask);
+	void CreateImage(vk::ImageTiling tiling, const vk::ImageUsageFlags& usage, vk::ImageLayout initialLayout,
+			const vk::ImageAspectFlags& aspectMask);
 	void GenerateMipmaps();
 
 	vk::Format format = vk::Format::eUndefined;
@@ -111,7 +111,7 @@ public:
 	FramebufferAttachment(vk::PhysicalDevice physicalDevice, vk::Device device)
 		: format(vk::Format::eUndefined), physicalDevice(physicalDevice), device(device)
 		{}
-	void Init(u32 width, u32 height, vk::Format format, vk::ImageUsageFlags usage);
+	void Init(u32 width, u32 height, vk::Format format, const vk::ImageUsageFlags& usage);
 	void Reset() { image.reset(); imageView.reset(); }
 
 	vk::ImageView GetImageView() const { return *imageView; }
diff --git a/core/rend/vulkan/utils.h b/core/rend/vulkan/utils.h
index 0caa16178..fe83eb52a 100644
--- a/core/rend/vulkan/utils.h
+++ b/core/rend/vulkan/utils.h
@@ -60,7 +60,7 @@ static inline vk::BlendFactor getBlendFactor(u32 instr, bool src)
 	}
 }
 
-static inline u32 findMemoryType(vk::PhysicalDeviceMemoryProperties const& memoryProperties, u32 typeBits, vk::MemoryPropertyFlags requirementsMask)
+static inline u32 findMemoryType(vk::PhysicalDeviceMemoryProperties const& memoryProperties, u32 typeBits, const vk::MemoryPropertyFlags& requirementsMask)
 {
 	u32 typeIndex = u32(~0);
 	for (u32 i = 0; i < memoryProperties.memoryTypeCount; i++)