iMac 27 inch 5k late 2015 runs laggy and slow

krijnpalm wrote:

Can't i just reinstall El Capitan without really erase everything. Or doesn't that rebuild/refresh the User/Library part? Gatekeeper turned that off in the system settings Security and Privacy so that is why it was red, didn't know that is was called Gatekeeper, but i turned it back on.

Hello again krijnpalm,

That's the problem in a nutshell. I don't know. In situations like this I prefer to get back to a known, good state as quickly and as easily as possible. Although an erase and reinstall is certainly a hassle, I know it will work. Migrating only user documents will probably work. If it doesn't, I know creating a new account and copying all files other than those in "Library" will work.

To be honest, there are other methods that might work too. And they might not. They might cause additional problems either right away or the next time you need to update your software. If that happens, then you might need to do an erase and reinstall eventually. It sounds like it might be easier doing that now and getting it over with.

What you describe is not something that people normally report. It is not something that should really be happening. Something, either on your old machine or with the "clean up" software has corrupted something. It may be possible to track down what that something is and correct it. Unless there are two things. This is just one of those situations where I will opt for a little short-term pain for long-term benefits and confidence. If someone else wants to keep trying to track down the problem, you can certainly work with them if you want. But for me, that kind of investigative diagnostic effort is not why I bought a Mac.

Can't i just reinstall El Capitan without really erase everything.

There is not a shred of evidence here that reinstalling OS X will solve your problem. You can do it if you like, and if you're lucky this might just be one of the rare occasions when it helps, but more likely you'll be wasting a few hours when you could be getting work done.

A other suggestion would be nice as alternative.

I made another suggestion yesterday. You haven't acted on it.

Hey

Has there been any solution to this? I have also been experiencing major lags on my 2015 m395x i7 iMac, especially when writing code. It feels like any drawing on the display takes forever. I already have a clean install behind me which did not correct the issue. Really frustrating...

We have just bought x3 of these with 16GB RAM for my office, as an upgrade to a 2012 i7 iMac.

All of them are truly terrible, obsolete, laggy, unusable, slower than my 10year old macbook Pro... and I'm not even joking.

Adobe Illustrator runs faster on my 10yo old laptop. In outline view mode in Illustrator (which should be quicker than standard view mode) is totally rubbish... takes literally seconds to update. It makes working on it impossible.

After Effects can't even play a 300px x 300px 3second long looping animation at a quarter resolution any faster than 9fps!?!?! again, my 10yo MacBook Pro and the 2012 iMac absolutely fly along at doing any of this... full resolution at 25fps with no trouble!!! Even playing a voice over MP3 file can't play properly.

Apple... you seriously need to sort your s**t out... this is absolutely disgraceful... it is quite clear that your iMacs simply cannot handle the 5k screen. We're going to be sending all 3 back.

Hello Robulation,

I suggest you start a new question specifically about your machines.

Hello,

I just bought an iMac 5K 27" and I get the same issue. No migration, just an all new installed system under Sierra, and everything is slow, very slow ! I tried to restore it, delete everything but nothing change.

Did you find a solution to this issue ?

Please see etresoft's suggestion above.