In this page, you can adjust some preferences that affect performance of processing C++ code.
Maximum concurrency of cache tasks
By default, the maximum concurrency of cache tasks is unlimited, that is, ReSharper will use all available CPU cores for building caches in background.
Reindex includers after preprocessor directives in an includee changed
By default, ReSharper does not reindex includers of a header file when preprocessor directives inside the header are changed. This helps improve performance, but it might also lead to stale symbols cached for includer files.