The difference was rather negligible I did a straight line run from the road sign near the Whiterun stables until I ran into the wall of the Honningbrew meadery with a character from both races while completely naked and unarmed. I did not use sprint, just the regular run speed. The Altmer took 32.04 seconds, and the Bosmer took 34.62 seconds.

To me this shows that the speed difference between races due to the height stat is rather minimal. I had been wondering about this for a while so I did a test and figured there may be others out there wondering the same thing. I was tempted to remake my Bosmer archer into an Altmer for a speed advantage until I tested it.

So, in the end I would recommend against using movement speed as a factor in deciding a race.

The range is between +8% (Altmer) and -5% (female Bretons and Khajiit,) and the difference can add up over longer travels. Try running with Delphine (female Breton) to Kynesgrove, and running with the Circle (two male Nords and a female Nord) to Ysgramor's tomb, as an Altmer, and you'll see.

It's not that big a difference on purely tactical scales unless you're a -5% and facing the Thalmor, as is often the case with me.

I don't know... The armor matters as well (my light armored female Breton outran heavy armored Nord Vilkas all the time). And only yesterday my Dunmer travelled from Riverwood to Kynesgrove with Delphine and Erik. All three in light armor, none particular encumbered. I adapted my speed to Delphine's, granted, but we lost Erik, the tallest, all the time.