**LONG POST! ONLY SERIOUS REPLIES PLEASE. Also I wouldn't mind a rioters opinion on this.**
Main reason being extremely poor in-game optimisation.
This game went from being playable on a 2010 mid-range laptop, to barely running on newer hardware. And the apparent system requirements stayed the same, ever since open beta, while they should be way higher.
Recently I got my old trusty 2008 Pentium D system out of the dust, cleaned it, installed a fresh windows 7 64bit system installation, put 4 gigs of DDR2 (dual-channel) ram, way more than the minimum requirements, and paired it with a fairly decent ASUS GT640 GDDR3 2GB version (while it's a 2012 card, it should be more than enough to power the ancient league of legends engine), and waited 4 hours for league to install (Yay crappy internet)
**Also I know that the pentium D is extremely obsolete, but believe it or not, it wasn't a weak processor even for its time, even though the TDP is ridiculously high**
After installation, I put the lowest settings possible, lowest resolution exclusive fullscreen(borderless was out of the question, because it puts a lot more toll on the CPU), turned off shadows, antialiasing, eye candy and such. And the result was playable in the first 20 minutes of the game (When absolutely nothing is happening on the screen.), after the game progresses and more lane minions appear, the game crawls down to a measly 30 fps, and dips even further down when a fight breaks out, to the point where it's entirely unplayable.
Also since neither the game client, nor the actual game is 64 bit, it consumes 1.7 gigs of ram in total. The client consumes almost 400mb, even with low spec mode enabled, and the game consumes 1.3 gigs of ram. And as some of you know, 32 bit applications on 64 bit actually consume more ram than they should, because of the 32 bit emulation. Now riot has stated that they would literally have to rewrite the entire code of the engine to make the game 64 bit, and it would take a lot of time to do so. So that's completely out of the question.
BUT, this game ran really good on the same system almost 2 years ago, never dropped below 50 fps, and hovered around 80 average.
Also the recommended specs are also fairly basic, they just require atleast a 8800gt with 512 mb of vram, or more. But the implication that you need a single core/single threaded cpu is pretty much stupid. If it was meant to be a 3ghz dual core cpu, then I can understand that.
I'm just worried that the game will be such an unoptimised mess, that it will struggle running even on the newest hardware available. Lately I had fps issues on my main rig (i7 4770k stock clocked, GTX 1070ti, 16 gigs of DDR3), and that is the main reason I'm writing this post. Seems like the snowdown map is a large hog due to its visual effects, BUT that's not the case entirely. Ever since the preseason patch, performance has been slowly degrading, as a lot of people noted both on the boards, and the league of legends subreddit, and riot is seemingly not fixing the performance issues, even though they claim they are.
Also the client had been hogging the cpu lately too, ever since the snowdown shop came live. Well not the i7, but the pentium D, it barely ran the client without dying lol.
**TLDR: The game performance is degrading, and riot is seemingly ignoring the issue.**
If you read the entire post, kudos to you, and have a blessed day