Advice Request Don't disable SysMain (previously known as SuperFetch)

[sepik]

Hello,
I found this interesting Reddit article of why you should not disable Sysmain aka Superprefetch.
I was wondering why my windows 7 machine boot time is so slow, without an av, still takes about 1.20 minutes to boot. 7200rpm drive used and defragged with O&O Defrag.
Then i enabled sysmain service. For sure it started to trash my HDD and CPU. Every boot it trashed and causes high CPU usage.
Surprisingly, after 4 days, my boot time went down from 1.20 minutes to 48 seconds(not suddenly of course).
Anyone here have such an experience?
-sepik

 

[Jaspion]

Disabling the service will disable more than just superfetch. Prefetch also depends on this service, so if you disable it you will also prevent the prefetch folder and layout.ini file from being populated/updated, which in turn means your defrag tool won't be able to optimize the file layout properly. In order to disable superfetch but not prefetch, you have to use the registry.

Spoiler

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters\EnableSuperfetch
0: Disabled
1: Apps only
2: Boot only
3: Apps and Boot (default)

Setting it to 0 or 2 will stop the disk thrashing.

I've been using it for boot only, and I've also disabled memory compression. For my old HDD laptop, with little CPU power and sub-optimal battery life, it's just better and more stable.

Edit:
For most modern computers, though, I'd assume leaving settings to default is best.

 

[plat]

Interesting. On here, EnablePrefetcher is enabled for apps and boot (3) in the registry, even though I'd disabled SysMain via Task Manager. I set it to (0), and used BootRacer to measure boot times. No difference at all. None.

I leave it enabled (default), it seems to do no harm on here.

 

[Soulbound]

I would not disable it.
Yes at times there is either high CPU or High Disk usage when system is loaded, but few mins later it goes back to normal and then its been normal since then (i had that scenario a month ago and then yesterday when i updated from 1909 to 2004 w10).

 

[sepik]

@Jaspion
Depends of what defragger is being used. If i remember this right, Perfectdisk and o&o can does have an option to respect layout.ini (aka stuff in prefetch folder). PD smartplacement is good. PDs Optiwrite is not, according to my testing. Usually when i do backup system drive image with macrium, i takes about 1.50 minutes to complete. However, with Perfectdisk Optiwrite enabled, i takes 3min to complete. Sure i was like wtf? Then i ran drive analyze, and "Optiwrite" wrote that imagefile to slowest part of the HDD. Then, without "Optiwrite" enabled, it wrote it faster free space available. I dunno why it does that, maybe it "intercept" all I/O writes by its own driver to prevent defraggin and optimal file placement. In other hand, i did smartplacement on my nvme(PD warned, not recommended when using SSD). Rebooted, then do SSD Optimize on the system drive. Surprisingly according to CrystalDiskmark, sequential(Q1T1) and random write speeds were faster then with O&O.

And, if You are the same Jaspion that did defrag script for the famous MyDefrag, You get my deeply respect!
-sepik

 

[Jaspion]

Interesting. On here, EnablePrefetcher is enabled for apps and boot (3) in the registry, even though I'd disabled SysMain via Task Manager. I set it to (0), and used BootRacer to measure boot times. No difference at all. None.

I leave it enabled (default), it seems to do no harm on here.

Just one note: without the service enabled, there will be no difference between using one registry setting or another.

@Jaspion
Depends of what defragger is being used. If i remember this right, Perfectdisk and o&o can does have an option to respect layout.ini (aka stuff in prefetch folder). PD smartplacement is good. PDs Optiwrite is not, according to my testing. Usually when i do backup system drive image with macrium, i takes about 1.50 minutes to complete. However, with Perfectdisk Optiwrite enabled, i takes 3min to complete. Sure i was like wtf? Then i ran drive analyze, and "Optiwrite" wrote that imagefile to slowest part of the HDD. Then, without "Optiwrite" enabled, it wrote it faster free space available. I dunno why it does that, maybe it "intercept" all I/O writes by its own driver to prevent defraggin and optimal file placement. In other hand, i did smartplacement on my nvme(PD warned, not recommended when using SSD). Rebooted, then do SSD Optimize on the system drive. Surprisingly according to CrystalDiskmark, sequential(Q1T1) and random write speeds were faster then with O&O.

And, if You are the same Jaspion that did defrag script for the famous MyDefrag, You get my deeply respect!
-sepik

Oh, yes. Some defraggers use layout.ini either by default or as an option, others don't. I am not familiar with the details of how PD works, but from what little I could look up I don't think the SSD Optimization had any real impact on the benchmark results you got. Maybe a background program or system event affected the performance and caused the difference.

And, yes, I'm the Jaspion that developed the MyDrefrag scripts. Thanks man.

 

[Evjl's Rain]

if you use SSD, disable sysmain + prefetcher asap. It will not affect (or insignificantly affect) boot and app start up time
if you have HDD, set superfetch value in registry to 2 (boot only). It will preserve fast boot time but won't affect app boot time much according to my years of experience + It will not cause excessive disk read/write

by the way, if you properly defrag or tweak your HDD computer, you can entire disable both superfetch and prefetcher with minimal loss in performance but with gain in HDD speed and never experience 100% disk usage

 

[ForgottenSeer 85179]

if you use SSD, disable sysmain + prefetcher asap. It will not affect (or insignificantly affect) boot and app start up time

Why?
Windows know if it's a SSD or HDD.

I wouldn't recommend disable anything such things as it only break stuff. Same for old page file which a lot sites recommend as "tip". In fact disable it, even with enough RAM reduce system stability problems. So let windows handle it

 

[Evjl's Rain]

Why?
Windows know if it's a SSD or HDD.

I wouldn't recommend disable anything such things as it only break stuff. Same for old page file which a lot sites recommend as "tip". In fact disable it, even with enough RAM reduce system stability problems. So let windows handle it

I don't really think windows is as smart as people assume it to be. I prefer to control stuffs myself and most of the time, it performs far better than the default settings
Superfetch and prefetcher are the first things I disable on a brand new machine. This speeds up the machine by a margin of day and night
I have been using my laptop without them for 6 years without any single issue

about page file, it's different because this can cause stability issue. It only works when there is not enough RAM or there is a task which requires a lot of RAM. Some apps uses pagefile to hide its real memory usage while there is plenty of free ram left => the more pagefile used, the faster SSD degradation or the slower the machine if on HDD
99.9% of the time, my RAM usage is <50% so I can happily disable pagefile to force all memory blocks to be written on RAM => faster
I tweaked my laptop to use only 0.7-0.8 GB of RAM on boot (total 8GB) so I have a lot of free RAM to use (some people have windows uses 2-3GB on boot)

I don't suggest everyone to do this. I do because I know what I'm doing

 

[ForgottenSeer 78429]

I tweaked my laptop to use only 0.7-0.8 GB of RAM on boot (total 8GB) so I have a lot of free RAM to use (some people have windows uses 2-3GB on boot)

I don't suggest everyone to do this. I do because I know what I'm doing

Not some but most of people have windows uses 2-3 GB on boot. When I bought laptop it was using 75% of RAM out of 4 GB Total. I added 4 GB extra and somehow managed to get it under 2 GB. But still it uses 1.8 GB on boot.How did you manage to get it such low(0.7-0.8 GB)? Becuase now I have to keep many softwares running due to online classes and in most of cases it reaches upto 85%. After that I have to face lag problem while switching the apps.

 

[Evjl's Rain]

How did you manage to get it such low(0.7-0.8 GB)

I don't know exactly how I can do it but it's a combination of disabling unused windows' services and apps. Trimmed down windows' components (similar to a lite version but with all necessary components). I disabled all apps on boot and only keep mostly needed ones (only 3). Open other apps when I need, like messaging apps
turning off superfetch can save some RAM
use a memory-friendly AV (Wisevector in my case). If I use Emsisoft, It will consume >=1GB of RAM => hate it, not enough ram to play games
finally, I use windows 8.1 9300. It saves up to 500MB more than windows 10 1903/2004 with the same tweaks. I usually have around 1-1.4GB RAM used on windows 10 but only 0.7-0.8 on windows 8.1

 

[LowEndMeister]

will disabling sysmain fix the framedrops i'm lately getting while gaming on my machine?

i3-6006u 8gb 2133 mhz ram, intel hd 520. 128 mb vram (for some reason, but it should be 1024)

 

[ForgottenSeer 85179]

will disabling sysmain fix the framedrops i'm lately getting while gaming on my machine?

i3-6006u 8gb 2133 mhz ram, intel hd 520. 128 mb vram (for some reason, but it should be 1024)

No. Instead, you should upgrade your hardware which is the problem here.
You can try increasing your RAM frequency which would boost your VRAM (obviously) too. 128MB for games is also too low. Even 1024 isn't much for gaming.