You will find the settings for your default caching mode on the Caching tab of RV’s Preferences dialog. RV has a flexible and configurable caching system. Much like the rest of the preferences tabs (aside from General) the Caching tab is a powerful place to optimize RV playback performance.
You can learn about how to optimize these settings in “Realtime/Streaming Playback from Fast I/O Devices.” In general we suggest you try to find the Lookahead sweet spot for your system, which involves finding the right size in RAM (usually pretty small 1 to 5 GB) and the right number of reader threads (depends on the CPU).
To prevent RV from crashing when making caching preference change please make sure nothing is in the middle of caching by turning off caching from the Tools menu and stopping playback before entering the preferences.