basically I have noticed recently that during any game that I am in if a hold the button to show the leaderboard my frame rate seems to drop or it looks like my screen is lagging but a soon as I let go and return to the game it stops instantly any help on how to fix as this is really annoying?!
Noticed the same thing. Its really doing my head in. A few friends are having the same problem too 
It’s a Forge map rendering issue. Essentially the engine is borderline able to handle the Forge maps in Matchmaking, and the Scoreboard in-game pushes it too far. It’s not the scoreboard causing the problem…it’s the maps’ rendering having issues.