Im having problems playing league.

Now this isn't a rant about the game or teethe current state of the meta but a personal issue I'm having playing this game. For me I've been platinum many seasons in league and always had a decent time with it but the biggest issues I've been having through out my time is playing this on my computers. I've played on Macs through out my time on league and each time I've done so the performance seems to be just dropping over time now. im currently using a 2014 Mac and the game feels unplayable for me in all honesty. Despite my ping being around 40 as the lowest potential ping i'm experiencing packet lose, frame delay and lag spikes in game. Its gotten to the point where I can't animation cancel and characters such as orrn seem to just freely hit me with the below auto without an animation even going through. So out of pure frustration with my inability to play the game I need to turn to you guys for a solution so please what can I do to fix this in the most cost effective way. This Mac has nearly nothing on it except the game. Here's the info for it Graphics is Radeon Pro 555 2 GB, memory 8 GB 2400 MHz DDR4, processor 3 GHz Intel Core i5