Think about all the others. Also if you played .org you would know that if anything it would have less spots.
Some players have tremendous lag as it is now, increasing slots would only make it worse. More players = more lag. More plugins = more lag. More entities = more lag. As you can see, a lot of anything causes lag and strain on the server
settings> video settings>graphics fast, smooth lighting off, particles minimal, render distance normal or lower, view bobbing off, and clouds off