When suspending to disk, does memory cache got dumped to disk?

My system has 64GiB of memory. I noticed it usually uses about 20GiB for cache. I wonder if I do "suspend to disk", does the cached part get dumped to disk as well, or is it written to disk before the system is suspended to disk? I want to reduce the actual total used memory before suspending to disk so that the system can wake up faster. Thanks