New Summoners Rift

First of all, really good job on the map, the art and theme is WAY better than the last and I feel it is 10 times better than the previous one. It also good with lag,except when there is a big wave of minions. Not sure why this is, but when theres about 15 or more minions, my frames go down from about 60 to 40. This isn't game breaking, but gets annoying when in the enemy or allied base defending or pushing. Anyone else get lag with lots of minions?