Pretty good, atleast for me. Almost all vsts I've downloaded work really well, windows vsts included with yabridge, sometimes the ui is janky (could be 'cause i use a tiling wm and pop-up windows don't agree with it) and a couple of random vsts don't work at all (includes both linux and windows vsts so idk if it's bad programming or a linux thing.) Reaper also has support for claps and lv2s which both work well.