Performance tuning tips

You can check whether performance slowdowns are caused by low heap memory by monitoring two indicators in the bottom right corner of the status bar: the general Memory Indicator and the Clangd Memory Usage indicator.

1. Press CtrlShift0A to open the Find Action dialog.

2. Start typing memory, then enable two options, Show Clangd Memory Usage and Show memory indicator:

   

3. CLion will add the indicators to the status bar:

   

   

   tip

   Both indicators can be switched on/off from the status bar context menu.

1. Select Help | Change Memory Settings from the main menu.

2. In the dialog that opens, set a higher memory heap value in the Maximum Heap Size field.

3. Click Save and Restart.

You can also change the heap size from the Toolbox app:

1. In Toolbox, select your CLion version and click the screw nut button on the right.

2. From the menu that opens, select Settings:

   

3. Go to the Configuration section and set a new value in the Maximum heap size field:

   

4. Restart CLion.

To increase the memory heap, you can change the -Xmx option, which sets the maximum heap size for the JVM:

1. In the main menu, go to Help | Edit Custom VM Options. This action creates a copy of the .vmoptions file in the IDE configuration directory and opens it in the editor.

2. Update the -Xmx value. For example, use -Xmx4096m to allocate 4 GB of memory instead of the default 2 GB.

3. Restart CLion to apply the changes.

1. Press CtrlShift0A to open the Find Action dialog.

2. Search for Registry:

   

3. In the Registry dialog, start typing clion.clangd.max.memory.

4. Set the desired value and close the dialog.

   

   tip

   You can also change the limit of clangd indexer memory here.

On-the-fly code analysis is one of the most performance-consuming processes in CLion. To lighten it up, you can configure the highlighting level for the currently opened file: none, syntax, or all problems.

• Use the inspection widget in the upper-right corner of the editor:

  

You can enable Power Save Mode or battery efficiency mode using one of the following options:

• As an alternative to disabling individual checks or files one by one, try using Power Save Mode. This mode disables all inspections and other resource-intensive background tasks across the entire IDE.

  To enable Power Save Mode, go to File | Power Save Mode.

  

• Right-click the status bar and select Power Save Mode. The Power Save Mode icon will appear on the status bar.

• CLion incorporates a complementary Clangd-based language engine which is enabled by default. Currently, it works for error/warning annotation, certain navigation tasks, code formatting via ClangFormat, and code highlighting with quick-fixes.

  In most cases, Clangd-based engine works faster than the built-in one (and sometimes provides more accurate results). However, it is not used for all operations. For example, Clangd provides the location for a quick-fix, while the fix itself is performed by the CLion’s own engine. Or, Find Usages employs Clangd to search through the files currently opened in the editor and the CLion’s own engine for all other usages.

  We recommend you take Clangd engine specifics into account when investigating performance issues. Use Settings | Languages & Frameworks | C/C++ | Clangd to experiment with the engine settings and see if they affect the performance on certain tasks.

• By default, CLion indexes all directories listed in CMakeLists.txt (including sources and include_directories paths) to ensure proper code resolution.

  Your project may include folders with binaries, logs, or build artifacts that do not affect CLion code insight. Indexing such folders can also be resource-intensive due to their size or location. In these cases, it is reasonable to exclude the folders manually: right-click the directory in the project tree and select Mark Directory as | Excluded.

  

  Once files are excluded, their symbols are no longer available to CLion. The following features will be disabled for excluded files: code completion, auto-import (unless the excluded directory is referenced by include_directories in CMakeLists.txt) , code generation, Find in Files (except in open files), navigation, and refactoring.

  tip

  If you are working in remote development mode, excluded directories will not be synchronized with the remote machine. See Remote with local sources: excluded paths.

• You can also exclude files such as logs or generated data by file type. To do so, go to Settings | Editor | File Types and add the pattern to the list of ignored file types:

  

  

tip

You can also exclude directories from test indexing without removing them from the standard IDE index. See Speed up tests indexing.

1. Go to Settings | Plugins.

2. Browse the Installed tab and disable the unnecessary plugins:

   

   You can also disable all manually installed plugins at once (the non-bundled ones) from the menu under :