How to reduce lag?

[Blockoman]

My RPG just hit 6500 bricks and it's getting very laggy in some areas.
All of the areas are spread out across Slate, but in certain places, it gets EXTREMELY laggy. This not only makes it hard to build, but almost impossible to play. I am definitely not going to quit working on it, but what should I do? I am thinking of moving everything except the Blockland folder to another computer.

[Ad Bot]

[kakashi11]

get faster interwebs

[Chrono]

Reduce detail. (In options and on the build)
Get a better computer.
Close other programs.
Fix and clean your computer

[Blockoman]

Reduce detail. (In options and on the build) It really isn't that detailed already.
Get a better computer. Easier said than done :/ There's a 40% chance I will.
Close other programs. Have done.
Fix and clean your computer Might do, soon.

[The Russian]

Either new graphics card or more RAM.

[deathrider]

keep all the people at one place dont let them walk far away or the game will wont to help them but thes other people walking away so it can only help groops but people are walking away so it has to stop to help them

[n0cturni]

Disable physics if you haven't already.

[Tojehusiza]

keep all the people at one place dont let them walk far away or the game will wont to help them but thes other people walking away so it can only help groops but people are walking away so it has to stop to help them

lolwut