They do slow down at some point, as said in the description. The glitches causes some of them to get stuck to the sides at random so use that to your advantage. Got all metals in a few minutes so difficulty level is low-medium. Despite the odd grammar and lack of depth, it's nice little short game to kill some time.
Getting all the medals:
Get Out You (secret medal)- Click the frog at the bottom
I Catch The Blue One-Double click the blue firefly.
Defeat The Spirit Of the Forest- No need to click the fireflies this time, just move the mouse over them to collect. Avoid the 'fire' orbs and touching any part of the forest spirit while shooting at the head.
15 Fireflies Catch- To catch all 15, you have to make sure to keep the frog (bottom) and spider (top) from eating any of the fireflies. Just watch the web and click any ones that get stuck before it gets eaten and keep the frog out of sight.