Your problems with playstore are with playstore and have nothing to do with the rom itself..
you are hitting the playstore at peak times or when maintenance or improvements or heavy downloads are occurring..
plus now that playstore has moved from just handling app to trying to be a music/movie hosted and anything else they can make money off of has become garbage..but that's just my opinion
I have had typical 3g speeds on this rom with no problems
on a side note you could try this fix to try to gain a better signal
Wrong UMTS signal indication on XT862 [Fixed!!!] - xda-developers
I've tested it over and over on Play store with two devices running different builds at the same time. Your theory doesn't match up.
Perhaps I should take a video to demonstrate if you still don't believe me. Same device. Stock 906 downloads things from the Play store and browses internet way faster than this rom. Both latest updates...
Edit: This is the situation from eariler.
Device 1: Droid 3 with Eclipse 2.2.2
Device 2: Droid 3 with SD 4.6
So I try downloading Go Power Master from the Play store: SD 4.6 finishes way before Eclipse 2.2.2
I uninstall and test it again: SD 4.6 finishes way before Eclipse 2.2.2 (At this point Eclipse is going only like 20kb/s while SD 4.6 is like 150kb/s or higher)
So JUST TO BE SURE I do it one more time with Google Voice: SD 4.6 finishes way before Eclipse 2.2.2
And one more time with osu!droid: SD 4.6 downloads it in like 6 seconds. Eclipse 2.2.2 was so sluggish in its download that after about a minute I gave up and hit cancel.
So at this point I figure "Let me switch back to my stock system and try it again."
Device 1: Droid 3 with STOCK .906 OTA rooted WITH bloat.
Device 2: Droid 3 with SD 4.6
On all 3 of my tests, .906 finishes ahead of SD 4.6 I also did some tests with the browser. The .906 stock device is still ahead of the game. Now at this point I figure "Ok, maybe it was just a bad flash. I'll switch back to safe system and reflash the sucker and see what happens"
At this point you get a repeat of what happened before. Look, I'm not saying you're wrong or anything, but the way this rom is designed, SOMETHING is keeping ME from getting high connection speeds over 3G. Maybe it was a fluke, maybe it was an entire coincidence that everything started working again when I was on the stock rom.
Then again, I've had issues on older roms with my Wifi. Sometimes it would play nice, other times it wouldn't want to work at all. Always depended on which rom I was on.
Any thoughts?