Is dramatic drop (>30%) in space usage normal?

Hello - wasn't sure if this belongs in Performance or Upgrades ...

I‘ve recently completed the Win7 –> Win10 migration and was quite surprised to find that space usage on my OS-Apps drive – after deleting windows.old – had dropped by ≈ 30% (38% adjusting for the hibernation file (which has now been disabled)):


All of my Apps (haven’t tested games yet) are still available and functional albeit with help from Compatibility mode. Potential causes I can think of:

1. There’s a bunch of Win7 functionality missing that I’ve not yet run into
2. Win10 has an amazingly smaller footprint for equivalent functionality (which would be even more amazing given the number of running processes and services vs. Win7)
3. I’ve done something wrong
4. Something else outside of my “circle of knowledge”

Should I be concerned?

Thanx in advance for your time and expertise.

If I had to guess, I'd say your W7 had a lot of restore points. It may also have had the W10 update, but that should be <5GB.

ritjesman said:

Should I be concerned?

Not unless you have further problems or functionality issues.

When I moved from 7 to 10, my used space on C dropped from 42 gb to 27 gb after all configuration was completed and I had reinstalled all my applications.

The bare 10 installation was 14 GB before any updates or configuration.

Since then, it's been as high as 47 and is typically in the upper 30s, depending on what Windows Update does. Quite a lot of variation in size, but very little variation in what apps I have installed. I run Disk Cleanup every couple of weeks.

You might see a big drop when you move to a new version of Win 10 via Windows Update.

Thanx for the timely responses, it's much appreciated. Looks like this is not a unique situation anyway, which is quite comforting.

The DISM//SFC "two step" found no errors.

I hadn't considered restore/recovery files; I use Reflect (with backups saved on different physical disk) and had never configured the Windows recovery functionality so Windows restore points are not typically on my radar. I also, however, use Revo Uninstaller which -- now that I think about it -- by default creates Windows restore points prior to each uninstall so I could have had a number of those and I suspect they'd have been in windows.old...

Hmmm -- just checked my Win7 clone on the VirtualBox VM used for upgrade testing. According to MS documentation Win7 restore points are saved in c:\ system volume information; that folder is only 1.8 gig (you need to take ownership to see the size/contents in its properties otherwise of course it shows zero size & access denied). So recovery point files do not appear to be the primary culprit. Oh well, I noticed a statement while researching this that restore/backup is disabled by default in Win10; if that's true this item should be a non-issue going forward. Does sort of make me wonder why there's a restoration partition created in a fresh Win10 install tho, unless that's primarily for OEM/branded builds.

Since I now know the reduction in space usage doesn't appear to be a danger sign I'm marking this as solved. Thanx again.

Although solved, if you have Reflect images, you could open them and see what has gone down.

mngerhold said:

Although solved, if you have Reflect images, you could open them and see what has gone down.

good idea - the image immediately after the upgrade should have the original windows.old fille ..