Optimization
Using Paper is recommended
Paper allows asynchronous chunk generation, which prevents server lag when generating locations for players. In plain Spigot, it has to be done on the main thread, which can cause lags. That's why it's strongly recommended to use Paper or Paper fork for this plugin.
World pre-generation
When a game starts, players are teleported to random locations on the map and chunks around their spawns need to be generated, which may cause a server to lag. This may be noticeable in larger arenas, running on weak machines, and it may even cause a server crash. For the default render distance (10), and a solo arena with 16 players, the number of chunks needed to generate on start will be equal to ((10*2+1)^2)*16 = 7056, which is a lot even for powerful computers. To address this issue, installing Chunky is recommended.
Chunky pre-generator
DOWNLOAD: https://www.spigotmc.org/resources/chunky.81534/
If you install Chunky, players' spawns will be pre-generated after a game finishes, allowing a smooth experience for the next game.
No additional configuration is required.
It's a soft-dependency, meaning it's not required for the plugin to work, although it's strongly recommended