Problem Details:
Windows 10
My osu! worked fine yesterday until last night. Osu started getting extremely laggy so I decided to give my laptop a rest and turned it off for the night. This morning I got back on and tried to play with my mousepad (no tablet connected). It works fine for a while, then the cursor gets extremely laggy. However, nothing else lags. The game runs fine but the cursor is choppy to the point where I can barely click a button. I plugged in my tablet and moved the cursor with the tablet and it was smooth. It was smooth for a few minutes, then that started getting as laggy as the mouse AND it started lagging the game itself a bit. Exiting out made the cursor perfectly smooth again once the osu process closed completely.
There's another problem. When I got on this morning my skin was reset to default and all the settings were default. I changed those back, and then I noticed that most of my beatmaps didn't show a star rating and the difficulties of each map were unorganized.
At this point I backed up all of my songs and scores and uninstalled and reinstalled osu. Nothing changed. I completely uninstalled the wacom tablet drivers and reinstalled them with the latest version, no luck. Opened osu.exe properties and turned on compatibility mode for windows 7, 8, disabled DPI scaling, still no fix.
When I exit out of osu the mouse lag remains for about 30 second then goes away and resolves itself.

This bums me out because I really want to play and all of a sudden this is happening. The only thing that I changed yesterday was removing the xbox app (I read on an osu forum that it disables input lag, and it pretty much removed most of the input lag with no issues)

Video or screenshot showing the problem:
When I recorded with Fraps, it slowed down too much to replicate the issue, but I recorded with my phone:
https://www.youtube.com/watch?v=wtC_f0MvEgQ

Here's screenshots of the star ratings disappearing:
Star rating disappears on all game modes and sometimes the difficulties are out of order. As I said above, I completely reinstalled osu and it didn't change anything. Problem appeared this morning after osu "reset" itself.
edit: forgot to mention the last screenshot shows how the stars show up on some songs

osu! version: 20170103.2 (latest)

When the lag happens, could you see task manager and see what happens?
Is osu! or a program taking 100% of CPU or RAM?
If so, take screenshots

Kao wrote:

When the lag happens, could you see task manager and see what happens?
Is osu! or a program taking 100% of CPU or RAM?
If so, take screenshots

Yep, here's screenshots:

Standing by in the menu/song selection/pause screen https://gyazo.com/79cf5bae6ca9e16c673969943b5caa6a
Gameplay (no mouse lag, running smoothly) https://gyazo.com/a6ff8a7a3356291f1c818980b6a3e515
After a few minutes (after the mouse starts lagging) https://gyazo.com/0d654b315442cdeac8ba4ed06b9ffb81

EDIT:
I switched my version to stable (fallback) and that seems to have fixed both my star problem and the lag problem. Looks like my issues are being caused by the latest version of osu.

Edit 2:
Nevermind, still having the star issue, not sure how to fix it :/ The fallback version also isn't as well optimized as the newer versions, but it's still running better. I really need some help with this because osu literally worked perfectly yesterday and I don't know what to do

This type of problem is kind of hard to fix, and I haven't found a solution yet

Try scanning your computer for viruses first

Kao wrote:

This type of problem is kind of hard to fix, and I haven't found a solution yet

Try scanning your computer for viruses first

Did a full scan (took 4 hours!) and it only found a few PuPs, so no viruses. Also, the star ratings are slowly coming back each time I launch the game, so looks like osu! is just slowly fixing the star problem by itself. Later I will test the game again today and see if it lags.

The star problem is probably caused by the lag
Since when loading up the song selection screen while your CPU or RAM is 100% could make it load longer than usual
Which causes some elements to not load properly or are delayed.

Try running osu! In compatibility mode and see if it still takes most of the CPU

Kao wrote:

The star problem is probably caused by the lag
Since when loading up the song selection screen while your CPU or RAM is 100% could make it load longer than usual
Which causes some elements to not load properly or are delayed.

Try running osu! In compatibility mode and see if it still takes most of the CPU

I set it to compatibility mode and here's the CPU:

Standby in the Song Selection after the game running for about a minute: https://i.gyazo.com/e8bf020627f4709e346 ... 6ed853.png
Playing a song, game running smoothly: http://prnt.sc/dsci8k
Playing, a song, menus, etc and the game suddenly started getting insanely laggy, osu using like 97% CPU. I couldn't even screenshot because it was so laggy. Then the game started fluctuating between 50-80 FPS while cursor remained extremely laggy: http://prntscr.com/dsclni

edit: also noticed that now the game also gets choppy, osu cpu usage goes way up for some reason, then the cursor lag starts

by the way, here's my specs:
8 GB ram
Nvidia geforce 940m 4gb vram
intel core i5-5200u @ 2.2-2.7 ghz
I have over 600 gb free in HDD space
playing windowed mode at 1366 x 768

Could you try logging out from the game and see if the CPU will raise?
Source: t/520119

Kao wrote:

Could you try logging out from the game and see if the CPU will raise?
Source: t/520119

I actually got on a while ago and the problem just fixed itself. Strange, but I guess my issue is solved. Thanks for your help

Windows 10 is such a mystery...