As [announced](http://euw.leagueoflegends.com/en/news/client/client-features/legacy-client-officially-retires-may-3rd), the legacy client will be retired on May 3rd. I'm not going to reiterate everything said in that post, but I highly recommend reading the FAQ as it addresses many common issues people have had with upgrading to the new client. Below we have some further information if you're having issues with the new client, to try and make the transition as smooth as possible!
#The new client lags for me - help!
First up, if you haven't tried the client in recent months and are basing this off of previous tests - please try again! The teams working on the updated client have put a lot of focus on making the client lighter, faster, and work better on lower spec computers.
If you are still experiencing problems, please utilise the "Low Spec Mode" as shown below. This option reduces the frills and animations around the client, and can improve performance (Personally I think of it as a "performance mode" rather than low spec mode - even mid to high machines can get a slightly smoother experience with less animations!)
#The new client causes my FPS to be lower ingame - help more!
If you find the client is causing you problems ingame, we've added a "Close client during game" option. This frees up more resources for the game client to use by pretty much killing the client in the background. This is a bit of a double edged sword:
Positive: More resources to be used ingame, squeezing out every last FPS.
Negative: Using this option will cause a delay in getting to the "end of game" screen - as the client has to open itself up again!
#It takes me a long time to get into the end of game screen with the new client
As mentioned above, this is normally caused by the "Close client during game" option being used. This option is only recommended if you **really** need it due to ingame performance being impacted. If you can turn it off, do that! You get to end of game much quicker that way.
#I miss item sets :-(
When the new client was being designed, item sets wasn't part of scope because honestly - it wasn't being used a huge amount. However, the teams heard the feedback, and are targeting a return of the item set editor for patch 7.10 (all going well, and no big issues being found!)
In the interim, apps and websites that allow item sets creation will still work - the new client just doesn't have an editor/creator (yet!). So if you're really really stuck, you can utilise those resources until we get the official one back in again ^_^
#I've tried using all these options and I'm still having issues - what now?
If you continue to experience issues, please [contact support](http://support.leagueoflegends.com) with as much detail as possible. Videos are especially helpful alongside logs so we can see exactly what is happening!
The new client is definitely different and takes a bit of getting used to (we've been using the old client for the past 7 years with fairly few cosmetic changes overall - this is new!), however with your feedback in the [Client Discussion Board](http://boards.euw.leagueoflegends.com/en/c/alpha-client-discussion-en), as well as a bit of time to navigate and get used to the new layout, hopefully the new client will become as natural as the old client :-)