In any match recently, I think since the Winter Wonderland update I have had sudden frame rate drops/ freezes the frame for like .5s to 1s intervals. This happens whenever something animation heavy is occurring during the match, for example an enemy Ana shoots me and the purple mist appears on my screen, it also happens with things like being stunned, Roadhog’s ult, Doomfist’s uppercut etc.
I have had no trouble playing on the same settings for over a year before. I have recently updated my Nvidia graphics card though.
It getting unplayable as how important reaction time is.
There are other steps you can do to check for variable FPS drops. I maintain a guide with most of these recommendations here in the technical support forum: