Last few years I've been my own boss mostly doing whatever I feel like with several years funds comfortable and no real pressure to do or die. Time hasn't really slowed down. I also took a year completely off work in 2016, that one also passed very quickly.

If anything, having new experiences is what seems to slow down time in my experience. Visiting new locations, doing and learning new things. I suppose more things will be new to the young than the old, so it would make sense as an alternative hypothesis.

I've also had a bad tooth ache since the day before Christmas I haven't been able to get dealt with since all the local dentists are off, and it feels like it's been the longest week in my life. Dunno if I'd recommend it as a way of prolonging the subjective experience of time though.

Another anecdote is that last year I quit coffee cold turkey, and a side effect was that time seemed to slow down significantly. A lot of people seem to be reporting this. Make of it what you want. Quitting coffee also sucks quite a lot, though not as bad as week of severe tooth ache.