if you have changed the HW acceleration value then i think you have read read the cautions as well ? as it is suits SOME n900s thats why it will show different affect on every device may it isn't suitable at yours so change it back if you think it is kicking your cpu rate up . plus you can try power top to check whether is it something else or HW acceleration . i have it changed on my device for like 5 months (not sure) and i text all day , about 600 texts and then use wifi and have above 20 beecons on my desktop and my battery still lasts for a day .