mac os 10.13.5 forced update?

I am using Word 2016. Took about two minutes to even get to the main screen to open documents.

Two minutes is only slightly longer than it should take. The slow start for Office 2016 was caused by Microsoft. Their Software Engineers are idiots. Because they don't understand sandboxing, they bundled all of the Office fonts into each app. So, every time you open one of their apps, the OS must load the fonts from disk. If you have a spinning hard drive, it takes forever. The only fonts that should be bundled into the App are those needed for the user interface.

You must learn to leave Office apps open so you don't have to wait for the Microsoft Stupidity penalty.

8 GB of RAM helps, but nothing is going to make High Sierra run faster with a spinning hard drive. I am running HS on a 2010 MBP with 16GB RAM and SSD. It runs quite well with High Sierra. Office only takes about 10-15 seconds to open an app, now.

If you don't want to install an SSD, restore from your backup and make sure the Settings in App Store System Prefs are set correctly to not install an update automatically.

I am backed up, but it's a pain to have to deal with this.

No it's not. Boot into Recovery and restore from your backup.

App Store System Prefs has the settings to allow system to auto-update itself. Otherwise it doesn't.

If you are still using a spinning hard drive, things will be slower.

Initially, Spotlight will have to re-index and caches rebuilt which will slow down the Mac for a while.

What version of Word? 2011 and 2016 should work, but both probably need the current updates from Microsoft.

Addendum to Barney's comments. Although a 7200 rpm 500 GB HDD, and 512 GB SSD — both optional were available for this MBP, the performance sounds like you have the default 500 GB 5400 rpm HDD. The storage interface is SATA 2 (3Gb/s), and not the faster SATA 3 (6 Gb/s) that arrived in the 2011 models.

You might retrofit a SATA 3 SSD in this machine and could experience some noticeable I/O improvement. MacSales, and Micro Center have SSD replacement drives. Micro Center has the 480 GB Inland SSD for $75USD. More than a few posts here have encountered challenges with Samsung 860 and T5 drives with High Sierra so caveat emptor.

Two minutes is excessive. Even for a laptop with a hard drive.

I'm also using a 2010 Mac, though it is a Mac Pro, and simply by design is faster than a laptop of the same era. 16 GB of RAM installed.

Main point of this: When I was running off of a hard drive, the initial launch of Word 2011 after a startup or restart was about 30 seconds. From the SSD I've been running from for quite a while now, Word 2016 is up and ready to use in 10 seconds. And that's the slow one. PowerPoint, Excel and Outlook are at most 5 seconds.

With two minute launch times, I'd be concerned the hard drive is dying.

Check your specs at Macsales.com or here: https://everymac.com/systems/by_year/macs-released-in-2010.html

Yours appears to be limited to 8 GB. Mine is a 13" that could go to 16.

Depending on what you do, 8GB may be sufficient. It probably would have been for me, but the RAM was cheap when I upgraded, so I went with 16.

I was at Micro Center Friday morning, stood drooling at the price of the Inland SSD, but as I haven't done any research on the company or the drives, I walked away from that very attractive price. So its mention is more for your price awareness. It may be an excellent drive for the price — I don't know.

I would be inclined to use Crucial, or even the Toshiba OCZ TR-200 SSD. A few years back, Toshiba purchased OCZ Technology, and it is a pre-acquisition OCZ Vertex 128GB that has seen daily usage in my 2011 Mac Mini since it was purchased in Sept/2011. Fast, and no issues at all — so I can recommend OCZ products. Newegg has the 480GB TR-200 for $123USD. I have also been using a Toshiba 2GB P300 3.5 inch, 7200 rpm HDD in an external Startech USB3.1 Gen 2 enclosure for Time Machine duties. Two years and no issues.