Why do computers slow down if left on overnight?

[boogielicious]

Why does this happen?  It is the same with my Mac at home or my PC at work.  Do the background programs create issues?

[billchao]

Eats up all the RAM, causing the computer to process memory through ROM, which is much slower. That's about the limit of what I understand of how computers work, and it's probably more complicated than that. I don't keep up with computer technology :-)

[nevets88]

IME, with Windows PCs that happens more often, rarely with my Mac. Processes that should have been terminated left running. That sort of thing. Unfortunately, you'll need to reboot once in awhile to clear it all up. It's the nature of the beast. I remember calling it the old "three finger salute".

[Jeremie Boop]

Interesting, I rarely see this happen. I hardly ever shut down any computer I have. There are times when a restart is required, but it's not very often and is typically only required after an update or install is done. If you are seeing this issue I would say you may want to run a malware and/or virus scan. Check the task manager, look for something that is using significant amounts of resources like memory or cpu. I would also say look at network usage for processes also.

[Shindig]

I'd be curious what your background processes are. I have a desktop computer connected to my television set that I use as part of my media center. It rarely gets reset. The machine is over four years old (I bought it in summer 2010) and doesn't lag when I stream something online (for example, if I'm home on a weekend during the day, pgatour's streaming golf). I pretty much only reset it when updates come out (although the LTS expired on the OS, so updates are for packages) that require it. Processes consuming (and not releasing, for one reason or another) RAM is an issue for sure. Can you tell us more about the relevant machines?

[iacas]

At night, the processes you're actively using drop, and if the computer needs RAM for some nightly tasks or things, you're active programs that are no longer active can be paged out.

Paging out RAM to disk is slow. Reading it back in is slow. Swapping is slow.

After you use your computer for awhile it should be fine.

Or get a little more RAM. Or quit applications you're not using much.

FWIW I regularly run a bunch of apps (Browser tabs can eat ungodly amounts of RAM, for some reason…), but I also have 32 GB RAM.

Which makes me feel old, as I remember when 4 MB was considered unreal…

[nevets88]

At night, the processes you're actively using drop, and if the computer needs RAM for some nightly tasks or things, you're active programs that are no longer active can be paged out.

Paging out RAM to disk is slow. Reading it back in is slow. Swapping is slow.

After you use your computer for awhile it should be fine.

Or get a little more RAM. Or quit applications you're not using much.

FWIW I regularly run a bunch of apps (Browser tabs can eat ungodly amounts of RAM, for some reason…), but I also have 32 GB RAM.

Which makes me feel old, as I remember when 4 MB was considered unreal…

I think SanDisk (can't remember exactly) now sells memory simms WITH SSD ON THE FREAKING SIMMS. No traversing the bus to get to the hard/SSD drive. That makes me feel old.

[Zeph]

I don't notice any difference regardless of how long my computer has been running, so there might be an issue with your if it does that.

[boogielicious]

Thanks for the responses gents.  For my work PC, I am not sure what IT has running in the background and I really can't mess with it.  For my home iMac, I don't think I have much running in the background, but I don't know what I don't know.  I don't have many apps on it.

[iacas]

Thanks for the responses gents.  For my work PC, I am not sure what IT has running in the background and I really can't mess with it.  For my home iMac, I don't think I have much running in the background, but I don't know what I don't know.  I don't have many apps on it.

Stuff is always running, though. Unix apps, daemons, the "OS" basically, Finder, Spotlight, Time Machine…

Launch Terminal and type "ps aux" and hit return.

Then type "top" and hit return (q exits). You can resize the window to see more on that one.

[boogielicious]

I got this

Processes: 150 total, 2 running, 7 stuck, 141 sleeping, 643 threads                                                                                                                                                                                                    09:27:05

Load Avg: 0.66, 0.97, 0.88  CPU usage: 0.94% user, 1.89% sys, 97.15% idle

But I did shut down last night.

[nevets88]

Thanks for the responses gents.  For my work PC, I am not sure what IT has running in the background and I really can't mess with it.  For my home iMac, I don't think I have much running in the background, but I don't know what I don't know.  I don't have many apps on it.

Corporate IT and the background processes/apps they set up. ARrrrrghh. One place ran an automated virus scan @ 11AM. I wanted TO PUNCH THE FIRST IT GUY I SAW IN THE FACE. WTF. Seriously? I needed every possible resource to do compiles around that time and it runs a virus check. Slow down my computer at the most inopportune time. ****! Screw the rules, I turned it off myself.

[Valleygolfer]

I find that the biggest problems are the browsers and plugins. Firefox has had a long standing memory leak that eats up a ton of memory after a while and usually is more so after a computer goes into power saving mode. The plugin is also associated with Chrome and will affect it as well. You have to kill the process and usually it will function fine after.

[newtogolf]

CPU's have to run all the time so the OS creates tasks for them to run or it just runs the idle processor.  Windows will also do things like index your hard drive for searching and other house keeping tasks when you're not active.  As Erik said, eventually the programs you're running get swapped out of RAM and into the cache on the hard drive so when you start to use it again, the OS has to load it all back into RAM which gives it the appearance of running slower.

[danL]

Another thing to consider is memory leaks. With the almost exclusive use of upper level languages, memory management has become "automated" by the language itself but this is almost always problematic. When previously used memory isn't freed up properly the system thinks it's still in use. Let a program with a memory leak run all night and it's nearly consumed all your resources.