Interesting I just saw this post tonight because it has been bothering me as well for the past couple months but I think I figured it out last night by dumb luck.
Open up Voice Command, tap the menu button>settings>shortcuts You will see a list of everything on your phone. Take a check mark out of every item that you would not use voice command for which for most would be everything except contacts if you just use it for calling. This is time consuming because after every uncheck it takes you to the top again. Give this is a shot and let me know if it works for you. I think once you have so many apps the voice command has to load everything and it bogs it down. I am no expert but it seems to have fixed the issue for me so hopefully it will do the same for you.
Ironically, just this morning I tried this exact procedure, in search of a fix. At first I thought it had helped, but after a short while of doing other things, "voice commands" became sluggish, again, and it turns out that if I go look at the list of shortcuts, they are ALL checked, again. I repeated this a few times, but for some reason all the shortcuts are getting re checked all by themselves!
UPATE: I just looked again, and figured out that after unchecking the items, I have to again press the hard menu button and select "OK", before closing out.
I'll go thorough all the unchecking, again, and see how it goes!
ANOTHER UPDATE: Even after unchecking EVERY shorcut, the problem still persists, for me.
UPDATE # 3: Okay, after a reboot (after unchecking all the shortcuts), I think it may be better, now. I'll let it run like this, for a few days of normal use, and see if the sluggishness issue rears it's ugly head.
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