1. Are you getting 80k Strength XP, or 80k XP in the "Experience Per Hour" section, indicating total XP (STR+HP)? 80K strength XP per hour doesn't sound awful. But maybe I just have low expectations ... I think sometimes people say they're pulling 120K Strength XP per hour, when really they're failing to realize that their HP is factored into that. I could be entirely wrong on this, though.
2. You're in hard mode, right? Normal would definitely deliver lower XP rates. Especially with Dharok's.
I've had problems using Dharok's, in Hard, for extended periods of time as of late. I'm not quite sure why and have been too lazy to upload logs. But when it has worked, at 95 strength/ 90 attack, I've averaged something like 85-90k Strength XP and a total of around 120K XP per hour with this bot.