Donno if there's a "cache" (or other) setting in Foobar I could change, or whether it's just a question of things getting fouled up once a number of processes have started running and clog up the laptop's memory, or what.
There are multiple buffer settings under File->Preferences->Network and File->Preferences->Advanced. They helped me when my main problem turned out to be old and very slow NASes, but I don't know if that will help you with your files being local.
(By the way: what software do most of you use?)
For PC playback I pretty much stick to Foobar2000. I bought a JRiver license but found it more frustrating to use for reasons I don't fully remember any more.
Though for serious listening to anything that's compatible with the system (stereo, AC-3 and DTS), I use Logitech Media Server and various players around the house.
If I'm sitting in the sweet spot in the living room, I use an Oppo BDP-103 for multichannel FLAC or DSD streaming, though it only works gaplessly if you use full-album files with cue sheets. Getting that to work properly for DSD was what made me think you might be dealing with DST files, but that's apparently not the case. The Oppo HAS to play DST off discs that have it, but it doesn't know what to do with DST when it's a standalone file.