usually for me this problem occurs when i use VST plugin which uses openGL graphics. vst 2 or 3 doesnt matter.
for excample, i have somewhere plugin - tube tech cl 1b. then i go into this very specific plugins settings, turn off use openGL. (or was it turn on, dont remember)
it requires DAW to restart, then after loading everything is solid and cool. no more lag in faders indicators or graphical equalizers (frequenzy etc)
i have no idea is it a bug or not, but it works.
maybe you have something similar