If you haven't tried, try defragmenting and doing a 'cleanup'.
If you are one that doesn't normally shut down at night, try doing a restart.
You could consult Gizmo on Win10 information.
There are free programs there and they seem knowledgeable, plus there is a chat and a forum available to ask specific questions.
First The Main Site:
http://www.techsupportalert.com/
Now a Windows specific page:
http://www.techsupportalert.com/windows
Their Forums:
http://www.techsupportalert.com/freeware-forum/
Site Search for Win10 Help:
http://www.techsupportalert.com/search/node/windows%2010%20help
Solve the Windows 10 100% Disk Usage Error With These 9 Tips
http://www.techsupportalert.com/content/solve-windows-10-100-disk-usage-error-these-9-tips.htm
Other bookmarks I have (kinda dated some may still work)
http://www.bootdisk.com/
http://www.ctrlaltdel-online.com/comic.php
http://www.extremetech.com/
http://www.fileplanet.com/
http://filext.com/
http://www.snapfiles.com/freeware/freeware.html
http://www.freewarearena.com/html/
http://www.goldenram.com/upgradedetect/upgradeadvice.asp?testid=ud03040220224427784426796
http://www.crucial.com/systemscanner/results.asp
http://www.newegg.com/
http://www.opengl.org/
http://www.pcpitstop.com/default.asp
http://www.sofotex.com/download/PC_Utilities/
http://www.pcnineoneone.com/
http://plugindoc.mozdev.org/windows-all.html
http://www.snapfiles.com/main.html
http://sourceforge.net/projects/btwincap
http://www.sysinternals.com/SystemInformationUtilities.html
http://www.techweb.com/
http://eeggs.com/
http://www.tweak3d.net/tweak/
http://www.tweakhound.com/
http://www.wugnet.com/tips/topicdisp.asp?topic=ie
http://www.allbootdisks.com/
http://www.driverfiles.net/
http://www.filedropper.com/09wave-
http://www.aplusfreeware.com/categories/web/FreeDreamweaverAlternatives.html
http://www.codecguide.com/about_kl.htm#variants
http://www.activewin.com/download/
http://www.adobe.com/
http://www.ahusoft.com/
http://audacity.sourceforge.net/download/plugins
http://free.grisoft.com/doc/1
http://www.axiomx.com/PixelToolbox/index.htm
http://www.rw-designer.com/picture-resize
http://www.baxbex.com/default.htm
http://www.betanews.com/
http://www.blender3d.org/cms/Home.2.0.html
http://www.bluechillies.com/
http://www.bsplayer.org/en/bs.player/product/about/
http://www.thesilver.net/
http://camtech2000.net/
http://www.cdromtreasures.com/
http://www.rinkworks.com/stupid/
http://cooltext.com/
http://www.cpusolutions.com
http://www.cybertronpc.com
http://websupport.wdc.com
http://www.daz3d.com/
http://www.deepburner.com/?r=download
http://www.trok.co.uk/milo/
http://downloads.techrepublic.com.com/
http://www.driverguide.com/
http://www.easyduplicatefinder.com/
http://www.edgies.com/
http://www.filehippo.com/
http://fileforum.betanews.com/
http://www.fookes.com/
http://www.freeapps.co.uk/windows/
http://www.simtel.com/welcome.php
http://www.gaiaonline.com/forum/computers-technology/free-ware-list-should-be-stickied/t.3946833/
http://www.freenew.net/
http://www.freebyte.com/
http://www.freeoldies.com
http://www.freephotoshop.com/index.htm
http://www.freewareplanet.net/
http://www.sofotex.com
http://www.gomlab.com/eng/GMP_LogoLibrary.html
http://site.magix.net/index.php?id=411
http://free.grisoft.com/doc/1/lng/us/tpl/v5
http://www.econsultant.com/i-want-freeware-utilities/index.html#business
http://www.archive.org/
http://www.codecguide.com/links.htm
http://www.logitech.com/index.cfm/downloads/finder/US/EN,CRID=270
http://www.griffinimages.com/psp.html
http://www.media-convert.com/
http://www.midilocator.com/
http://www.netfor2.com/copy2.html
http://www.albion.com/netiquette/
http://www.opensourcewindows.org/
http://www.tigerdirect.com
http://www.opengl.org/products/platform/C5/
http://www.openoffice.org/index.html
http://www.winsupersite.com/
http://www.qualibyte.com/pixelformer/
http://public.planetmirror.com/
http://www.freshdevices.com/confirm.html
http://shark007.net/vistacodecpackage.html
http://www.snapfiles.com/
http://www.sofotex.com/
http://www.space.com/php/multimedia/downloads/wallpapers/
http://www.planetside.co.uk/terragen/resources.shtml
http://www.naturalreaders.com/
http://www.celestiamotherlode.net/catalog/fictional.php#1700
http://ghostfox.org/index.php?option=com_frontpage&Itemid=1
http://www.imgburn.com/
http://www.the-demo.com/links.php
http://www.sofotex.com/top_downloads.html
http://www.tweakvista.com/tweakvistautility/
http://www.it-mate.co.uk/
http://vectormagic.com/
http://www.bestvistadownloads.com/download-vista-software.html
http://www.drewstruzan.com/
http://www.xtort.net/index.php
http://www.carolsvault.com/windows-vista-compatible-freeware/
http://www.world-machine.com/gallery.html
http://www.geeks.com/products.asp?cat=SYS
http://www.barebonekit.net/index.asp?FSCat=302&url=IND&iFromFeatured=1
http://www.computerworld.com/
http://www.cray.com/home.aspx
http://www.ecsusa.com/
http://www.directron.com/under10.html
http://www.newegg.com/
http://www.pcwebopedia.com/
http://www.pcworld.com/news/article/0,aid,114473,tk,wb030804x,00.asp
http://www.belkin.com/
http://www.old-computers.com/museum/year.asp?y=1986
http://www.bestbuy.com/
http://www.wdc.com/en/
Its been awhile since I have used my old bookmarks but you might find something helpful, just remember to specify win10 if the site works.
LOL I had a vista pc hahaha.