I'm not one for these sorts of apps as I generally prefer to do the same stuff manually -- the only exception so far has been KCleaner, a prior GOTD & the only one that managed to clear the [broken?] Edge browser cache on this copy of Windows. That said, from the comments on the download page, in case it's of any use to anyone...
"Can we please have some objecctive assessment of this Software to really assist decision making either way?"
WinSysClean X11 PRO & similar are fine to try as long as you've got a good, recent, disk / partition image backup that *you know you can restore* to put things back in the rare case it's necessary. [That part about knowing you can restore the backup is pretty important, as I've found several backup app USB sticks that will not work with UEFI & Secure Boot, e.g AOMEI, EaseUS etc.]
If your having a problem with Windows, WinSysClean X11 PRO **may** help -- you may decide it's worth a shot since there's very little you can do besides running a Windows Troubleshooter, which in my experience usually just wastes your time. Windows Is Not self-repairing. Windows version upgrades requiring a reinstall can usually repair Windows & help by clearing away a Lot of clutter, but it's uncertain if Win10 will see any more of those. You can perform a repair reinstall of Windows, though it doesn't seem to clear out as much leftover junk as upgrading. Windows does have a System File Checker tool, but I've never seen it help with Win10/11.
zdnet[.]com/article/the-ultimate-windows-troubleshooting-trick/
windowscentral[.]com/how-use-sfc-scannow-command-fix-problems-windows-10
Most repair attempts & alleged performance boosts rely on WinSysClean X11 PRO cleaning the registry, which generally amounts to clearing known caches & deleting entries with broken links to missing files &/or registry entries that do not exist. Logically that should not ever cause any problems, but software can contain legacy code that checks for & requires certain registry entries that no longer serve any purpose, so deleting them can break stuff. Logically it likewise shouldn't fix anything either -- a broken link shouldn't do anything because it's broken -- but some people report using a registry cleaner fixed their problem. The smaller the registry's physical size, the better, since it has to be read or parsed, but it takes deleting a Huge number of entries to make a real difference, so WinSysClean X11 PRO is *probably* not going to make a big difference in this respect.
WinSysClean X11 PRO can clean up a lot of junk files Windows & your software leave behind. Windows has Disk Cleanup & Storage Sense, which can help, but neither will get everything, & while WinSysClean X11 PRO does a better job, it won't always get everything either. There's just too much junk left behind. While a bunch of files, each taking up 1MB or less won't matter, you can easily accumulate 5-10GB, or more. And that can be a bigger problem than you think, because while you may have plenty of space left on an SSD, performance decreases, sometimes dramatically, if you exceed 50% of its capacity.
Regarding some comments concerning SSDs...
By default Windows will optimize hard disks & SSDs on a schedule -- it's best not to turn that off, as Microsoft has found SSDs need an occasional defrag to keep Windows performing optimally. Otherwise optimizing SSDs will run a TRIM function, supplementing the TRIM that's likely also run by the SSD's firmware automatically.
Most all hard disks / SSDs record some data concerning their status & performance that you can access using something like Crystal Disk Info, a free app that reads data stored in a drive's S.M.A.R.T. registers. What's recorded & how varies by make & model. Pay attention to past & current temperatures, as both conventional hard disks & SSDs can suffer degraded performance etc. if temps get too high. SSDs can have quite a bit of variation in both their design & the components used, and that goes a long way towards determining their theoretical lifespan & warranty duration. Their recorded S.M.A.R.T. data normally includes some indication of remaining *theoretical* life expectancy / remaining warranty, though how that info is reported also varies... where one drive might show a steady decrease in life remaining, another may drop 1% on day one, then stay at 99% for however long, or it may show 100% forever because the SSD's designers never bothered to make that register active. And that does reflect *theoretical* lifespan -- an SSD can fail at 100% or last years after it reaches 1%.