Battery is an integral part of the power system.
A non-functioning battery can cause problems including slowing down the computer.
Graphic intensive applications draw additional power from the battery.
"Service Battery" means replace the battery as soon as possible.
"Replace Now" means replace the battery now.
I'm having the same issue. Early 2011 Macbook Pro, 8GB RAM, about two years, pretty intensive use of battery. Couple of weeks ago, the status was 'check battery', but after I updated the SMC firmware, the status changed to 'replace now'. So now my mac gets really slow after a few minutes of use. It startsup ok, but later on, even when typing an adress in Safari takes a while to the charecters appear after I hit the keybord, and the video playback is terrible. This is very annoying. I will absolutely have to replace my 248 cycle dead battery much sooner than what I'd expect.
No guarantees but this worked for me:
My Mac started running really slow when my battery died. I have a MBP (early 2011) with a built-in battery.
I checked Activity Monitor (/Applications/Utilities/Activity Monitor) and found that PID O, kernel task, was taking up 500% of CPU. Normally, it's < 5% at all times. I searched online and found the following fix. Though my battery was still dead, performing this fix solved my problem. Speed improved to normal. I still had to get my battery replaced but now my MBP is completely okay. I would check Activity Monitor. If PID 0 is taking up a lot of CPU %, you may want to try this.
BTW, the fix removes a .plist related to SMC thermal control. I don't know why it works but it worked for me. It looks a little scary to do but I had no problems and it worked instantly.
Here's the link: http://www.rdoxenham.com/?p=259
Don't follow the advice in the main text. Follow the advice in the comments, by "bryazana:"
1. Go to About this mac under the apple in the upper left and click on More info
2. Click on system report
3. make a note of what it says after Model Identifier
4. go to your master drive – System -Library – Extensions – IOPlatformPluginFamily.kext -Contents – Plugins – ACPI_SMC_PlatformPlugin.kext – Contents – Resources – find the name from step 3 and move it to a folder that you can find again if needed.
3. Restart and you’re done
I hope this helps.
I too ahve a MBP early 2011 version... I had struggling with a slow display for over two months. i formatted my hard drive, reinstalled the OS, backed up all my data to my external drive but all the effort went in vain...
I really have no words to thank you for sharing the steps!!!
It worked for me... Thanks a ton bud.