It's no secret that Spiral Knights has some java issues when it comes to long play sessions. While a better garbage collector would be best in the long term, in the short term players have been using a tactic to manually crash their game so that they are marked as "disconnected" which allows them to restart their game and prevent stutters/jumps from negatively affecting gameplay.

So basically my suggestion is to add a button into the escape menu that disconnects your player and closes the game immediately afterwards, allowing for players to clear our their game cache without using a task manager or disconnecting their internet temporarily. A heads' up what this does would be necessary via the prompts. This would at the very least allow players to not risk crashing their game in a difficult level that they cannot join back in on, such as a shadow lair, and have the manual crash not work and thus lose out on the run or have their teammates wait on a game master to help bring them back in.