As a technical MC player I have noticed that contraptions incorporating pistons moving large amounts of blocks have become excessively resource intensive on the client since older versions. This has become apparent when I migrated a contraption incorporating a tree farm and TnT blast chamber from 1.15.2 to 1.16.1, and despite having upgraded to a brand new PC with far superior specs than the PC I used in 1.15.2 the lag is unbearably worse:

To Reproduce:

1. In 1.15.2 setup a contraption in which pistons move a large amount of blocks continuously, expand the system until you notice the clients frames begin to drop.

• Observe the clients framerate 

2. Construct the same contraption in 1.16.1

• Observe the clients frames dropping significantly lower than in 1.15.2 and eventually crashing the game