Weird timeline and marker behaviour

Hi everyone,

newbie speaking -

all of a sudden, without hard- or software change, mid-editing the same files in the same project, the trimmer window started lagging and then the time marker did not follow my scrubbing anymore. Markers lagged - I could place them but didn´t see them before popping the clip into the timeline. Now Premiere itself lags when opening (I restarted app and computer a few times), it loads the files alright and shows them in the preview, but the Premiere window itself and the workspace (i.e. everything dark grey) only appears a few moments later. And when I move the time marker in the time line, it scrubs in the trim window but NOT in the timeline. Eurgh. What can I do? FAST?

Not giving hardware specs because it worked fine for two weeks without any changes (including Win updates).

Thank you!