I just read a chapter in Thomas Mann's "Magic Mountain", which goes into exactly this - boredom or uneventfulness drags out time in the present, because nothing

I just read a chapter in Thomas Mann's "Magic Mountain", which goes into exactly this - boredom or uneventfulness drags out time in the present, because nothing keeps your mind occupied, but contracts it in hindsight, because longer units of time like days are basically the same and "collapse" into one in your memory. Excitement / novelty on the other hand do the opposite - time seems to go by faster in the present, but you make lots of distinct memories, so looking back it all appears longer.