My boyfriend takes HOURS to respond to my texts... am I overreacting?

...and we're long distance!! He'll promise me that he'll text/call, and 75-80% of the time he doesn't. He KNOWS this drives me insane and just today we got into a little argument about it and he told me he's really trying, but I just don't get it. This is the only thing we ever disagree about. I'm not just going to go and break up with him because we've been together for 3 years but this has been a problem on and off and actually broke us up once for a few months a little more than a year ago. Here are just some examples of what he does.. I don't know if I'm overreacting but it honestly drives me insane. This is an issue anywhere from 5-6 days of the week, unless something particularly special is happening.  Am I wrong?
(This one is from today and it's almost 12 and he still hasn't responded)
(This one is from last night and he was home but didn't call me) 

Vote below to see results!