Long v2 1920x1080 (my screen resolution)
Used ROM Toolbox - Boot Animations to install it, first time took a long time booting, first circle part was fast and smooth, rest was pretty smooth, didn't seem to lag, did hang up twice (think the loop started again), took I'd say about three minutes, but did eventually boot up. Popped up with notification about System process not responding, screen flashed a few times. Lost connection/went roaming, warning again. Then no issues.
Rebooted
Second time was perhaps a little faster, but still at least two minutes, hung up once (again, think loop started again), same system process not responding immediately when phone turns on. Warning twice. (Not sure if buggy wifi result of processes restarting. After about two minutes, everything seemed working (wifi went from great to no connection, but I know the 5.0.1 ROM I'm running still has the Lollipop wifi bug)).
Rebooted
Again, about three, maybe even four minutes booting, wasn't actively watching so not sure if hung up, system process not responding at beginning, screen flashed (think the UI had flash to reset). No further issues.
Anyway, the boot animation is causing immediate process failure as the phone turns on, but really nothing after that.
However, that might be your answer as to why people are getting stuck in boot loops. The animation is affecting the initial system processes.
I might keep it, I might now. It looks good, but takes a while, and the system processes warning, though it doesn't seem to affect the overall usage of my phone, would get annoying, and shouldn't be happening in the first place.
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UPDATE:
Used ROM Toolbox to re-install original animation, took about half the time (read: normal boot up time), no system process error, though screen did flash after about thirty seconds, data switched to roaming, then switched back.
Rebooted.
Same quicker time, no process issue, slightly long to connect to Verizon network, screen did flash (only apps, not the whole screen, but I think that's the ROM). Anyway, original boot animation not messing up.
So your animation is doing something to mess with the system processes.