Welcome!

I guess it is just so much easier to support botting on all three platforms using the platform-independent legacy Java client rather than using three native NXT clients. Also most Runemate users seem to bot on OSRS, so there is not much demand for NXT support.

I believe Jagex is intentionally breaking the legacy client almost unplayable to speed up migration to NXT

Pretty much every bot is throwing exceptions today :(

Works okay but the bot could wait a little longer before opening MakeX again. Right now it restarts fletching 4 times per inventory if my client or network lags even a little

The Java build bundled with RuneMate for Linux is broken. It does not contain libattach.so library required to attach to game clients. You can either change Java installation directory in the launcher script to your system's Java or symlink the missing files from your system's Java to RuneMate's...

If it slows down over time, the reason could be CPU overheating or running out of RAM. You can also try tuning OSRS CPU performance settings in RuneMate