it must be a bug because it lasts too long and it does not happen when i combo. only after all text particles (which spell $3 or -$13) disappear, the game stutters when the first one reappears.
to fix this, instead of spawning and despawning the text particles completely, the text just gets changed to “$3” when earning money and to “” when the text should disappear. this way, the text particle does not despawn but it just becomes invisible, which is much more performance-friendly.