The Riot dev team never ceases to amaze: in the article linked above, they’re putting right out in the open some of the major issues with the League client and detailing their plans to address them:
TL;DR: Over the next six months or so we’ll ship a number of changes and improvements to the League client’s backend infrastructure. To track our process, we’ll be sharing specific targets for two main client performance metrics: client bootstrap time (how long it takes for the client to boot up) and champ select lock-in time . In the process of improving these metrics, we’ll also be tackling things like bugs, crashes, etc. Put simply, our goal is to fix the client .