VLC lagging when playing x264 1080p mkv file without installed a Battery

Mac Zero: *There is never any good reason to operate your MBP with the battery removed.* Doing so does not prolong the life of the battery or the computer, and the computer's clock speed is automatically reduced by half when you do so. That accounts for the lag you are seeing. It is intentional, because when the computer is working extremely hard it may require more power than its AC adapter can provide, and it's designed to draw the additional power it needs from from its battery under those conditions instead of tripping the overload protection in the AC adapter, which would cause the machine to shut down without warning if the battery were missing. Slowing the CPU when the battery is removed reduces its maximum power demand to what the AC adapter can safely provide.

Once the battery is fully charged, charging stops and does not begin again until the charge level drops to 93%. This allows the battery to remain cool most of the time even if the AC adapter is nearly always connected and the battery remains in place. Apple's smart charging algorithm also limits the heating of the battery and the adapter even while it is being charged, by varying the rate of charge throughout the charging cycle.

In short, leave your battery in place at all times. Your MBP will perform better in everything you use it for, you will lose nothing from your battery's useful lifespan, and you will never lose data to a power outage.

If your first battery lasted only 14 months, it may have been defective. What does System Profiler > Power tell you about its Full Charge Capacity and Cycle Count?

That's just plain bad advice. Follow it if you like, but I recommend not doing so.

The best available summary of useful advice about the care and maintenance of Apple batteries is here:

http://discussions.apple.com/thread.jspa?threadID=1764220

It's more complete than anything that even Apple has published (though there are links in it to Apple's publications on the subject).

Those battery statistics suggest that the battery died before its time. You may want to take it to an Apple Store or an Apple service provider to be checked out. Apple says a *properly maintained* MBP battery of that vintage should retain 80% of its original full charge capacity after 300 cycles, and yours hasn't come close. I don't know whether you've maintained it properly (if you've been removing it whenever AC power is connected, you haven't), but you can at least ask Apple to replace it without charge. The worst that can happen is that they'll say no.