While I'm not experiencing any in-game lag, I wanted to report issues with the Particle Collection Game.
There is a slight delay in directing (via keystroke or mouse click) the collection bucket and its subsequent movement.
As a phase advances the incoming particles jump/shift to the right resulting in missed particle collection (and disorientation on my part). I have noticed that numbers of players on the map can aggravate the jumping/shifting. However, particle jumping and shifting occurs regardless so moving to an isolated instance is not a guarantee of improved performance.
Added: Sometimes games end prematurely.
I experienced and reported these same issues last year. They have returned.