Why is my toilet flushing slow

[Jayjay23]

I took the toilet off. No clog. Put it back on and it's still has the issue of water rising before draining very slowly.

Took 2-3 flushes just to get rid of toilet paper.

 

[oz-plumber]

Typical signs of venting issue.

Air not being emitted from the drain when flushing.
It could also mean there us a blockage down the line somewhere.

Is it only the toilet that is slow to drain or are there any fixtures with similar problems?