I have recently discovered a very odd bug in Minecraft in which the speed of coordinate detection and related movement increases as the number of entities (only armor stands have been tested) increases. When I had only a few armor stands and used the [62,72,23,r=0] tag (coordinates are made up here) coupled with command blocks to create a movement system, it was somewhat slow. However, when I summoned more armor stands in with the marker tag, invisibility tag, and custom name S (about 50 of them) and moved around, it detected my position and moved the armor stand much faster. I did not alter the command blocks in any way. I thought this may be a byproduct of the new 1.9 collision system, so I tested it in 1.8 and got the same result. I now knew it wasn't the collision system, but decided to test one more thing. I added all of the armor stands to a team and set the collisionRule to never and got the same result once again. I then entered debug mode and it produced a tick speed of 19.998 per second (which is nearly perfect), meaning that I am not lagging. My FPS doesn't change one big either (unless I summon over 400 armor stands which causes my game to lag). I'm not sure what this could be, as more entities should not at all affect the speed of coordinate detection. I haven't tested if this increases the speed of other operations in command blocks, only coordinate detection via the [24,26,12,r=0] method. I have a short video showing this in action here: https://www.youtube.com/watch?v=NFL3HhkEds0

If you would like to recreate this effect, do the following:
Create a void world and go to the coordinates 0, 0, 0 and set up some command blocks at the coordinates 5, 5, 5. First create a repeat command block set to always active with the following command:
1. /execute @a[0,4,0,r=0] ~ ~ ~ tp @e[type=ArmorStand,name=M] ~-1 ~ ~
Then create a chain command block after it set to always active with the following command:
2. /execute @a[0,4,0,r=0] ~ ~ ~ tp @p 0 4 -1
Then type this in chat:
3. /summon ArmorStand ~5 ~ ~5

Then teleport yourself to 0, 4, -1 (facing south) and walk forward. The armor stand should move to the right at a decent speed. Now summon the armor stand again and summon in around 50 armor stands with a different name (they can have a name, marker, invisibility or not, it doesn't matter). Now walk forward and you should notice that the "M" named armor stand moves to the right much, much faster than it did previously. I'm not sure what other problems this buy may cause, but it'd be nice to have it fixed. Thank you for reading!