Another speed test site is https://testmy.net
The site claims superior accuracy (which I can't confirm but probably someone here can evaluate one way or the other). The site offers a number of test options and other amenities.
I'll have to try these other sites to see how they compare.
Edit: Just tried testmy.net vs. internetspeed.my:
testmy.net: download 533.5 Mbps upload 17 Mbps
internetspeed.my: download 549.1 upload 19.2