I tried upgrading OS from El Capitan to Sierra, but Sierra did not work so I used Time Machine restore to revert back. I didn't erase hard drive, just hooked external hard drive to Mac and chose to restore using Time Machine backup.

But now I notice that Mac is bit slower when activating apps. When starting up, it takes maybe 30 - 60 seconds longer to get LibreOffice and Firefox running. Is that normal?

I've been trying to find out if I could erase the drive and restore system again from Time Machine backup.

According to this, one has to erase Sierra completely, but I have no way to clean install El Capitan from scratch. Only thing I have is Time Machine back-up. http://www.macworld.co.uk/how-to/ma...ierra-el-capitan-remove-macos-sierra-3581872/

My question is in 3 parts:

  1. It doesn't really bother me by itself, but I got tiny worry that what if I weakened system, security or something like that by restoring El Capitan without erasing drive first?

  2. Would it be possible to erase drive and then use Time Machine back-up to restore system WITHOUT installing OS first from another source? (I don't have El Capitan anywhere so if just Time Machine alone can't restore drive, then I'll ignore the tiny lagging)

  3. Should I make Time Machine back-up now, would the tiny slowing of system carry on to any future restores (in case I do clean system restore)?

  • Whenever reverting to an earlier OS, it's best to wipe and start fresh. The problems you are having is most likely caused by not formatting first. – Allan Jul 4 '17 at 13:04
  • @Allan Can I just wipe the drive and then restore directly from Time Machine back-up? Would it work like that? And if I make new Time Machine back-up now and use it, could it bring problems over? – Gazudara Jul 4 '17 at 16:26
  • Did you do a "full backup" including system files or did you just back up your data (i.e. Documents, Desktop, User Settings, etc.?) If the first, then yes, you can wipe and re-install. If the latter, you need to create install media first, then wipe, install and then restore your data. – Allan Jul 4 '17 at 17:53

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