Since Season 5, I've been running into Video lag / freezing with the new Ground STFs that shouldn't be the video card because there is no problem with the rest of STO on both high and low settings. And there is no problem with other programs as well.
But in the STFs, it doesn't matter if on High or Low Settings, the problem still persists. And tends to happen during combat.
Have you also noticed the lag appears when those weird 'Adapted' signs hover on top of the NPC's?
Last time I had massive hickups on ground STF's and everytime it happened it was with the weird Adapted signs and it seems like there are too much 'Adapted' signs/text being drawn at one time on the screen.
I was getting a pretty bad frame rate hit after Season 5 rolled out, and I would activate abilities like Sonic Pulse or Neural Neutraliser, especially when there were other layers of effects behind or in front of the effects from my powers. I turned off Anti-alias in the graphics options and it seems to have settled down now.