Hi Sarah, Well, B* is not that good for online gaming. Your Download and Upload speed are fine, but your Ping is 37. The lower the ping is the better the gameplay will be. Online game play depends up on Ping, not the Upload or Download speed. The lagging usually happens if the ping is high. Remember, these things are out of our control. The best ways to improve online gameplay is, use Wired connection, disable other internet related tasks like sharing, downloading etc. Ethernet is more reliable and faster for online gaming, so hard wire instead of using wireless if not already.
However, we can do some maintenance on your Mac. So if there any problem with your Mac, these steps should fix the problem. Goto Applications > Utilities folder and open Disk Utility. In Disk Utility, select your hard disk. Click Repair Permission. Then click Verify Disk and if asked to repair, click Repair Disk.
Then download and install this utility, Onyx from here : http://www.macupdate.com/app/mac/11582/onyx
(download the correct version of Onyx, you can see the different versions of Onyx in the bottom of that site)
Open Onyx. In Onyx, click on Maintenance tab. Select Rebuild tab, check all boxes and then Execute. The under Cleaning select System and User and check all boxes on both and Execute. When it finished, restart your Mac. Try LoL game.
BTW Sarah, I don't think there are any buffers or flow regulators you can setup when this happen. Let me know how it goes.