Q: Can Magsafe power adapter affect performance when plugged in?

NightRelic wrote:

 

I have a mid 2012 15 inch Macbook Pro. It has a 2.3 GHz Intel Core i7 processor. The magsafe power adapter is 85 watt. I've noticed when I have it plugged into the machine and I'm working on it I have a lot of issues. When using the internet in both Firefox and Safari after a while it starts to choke. The program freezes and the timer starts spinning. Sometimes it will unfreeze for a while, then freeze again, but eventually I have to force quit the program. It happens a lot less when the magsafe isn't plugged in, maybe not at all.

 

If the magsafe is plugged in when it goes to sleep after a period of inactivity or when I close the screen, if I open it back up or if I try to reactivate it when I haven't closed it, nothing happens. The screen remains dark. I'll push the track pad and the space bar. Nothing. I push the power button. Nothing. I push them all over and over again at random. Finally the screen will come up and the timer comes up too. Sometimes it will have to cycle through what looks like part of the start up procedure before it will show my log in. The cursor will be frozen for a while. Then the screen will go black. Eventually the screen will come back up, sometimes the cursor will still be frozen at the point. Eventually I can get the cursor over the log in. At first it won't type. I'll hit the first letter of my password and the backspace alternately until finally a letter will type. At that point I can log in, but the desktop is slow to pop up. Sometimes the clock will spin for a while once it does. Sometimes all the programs will take turns not responding. I can watch this because most of the time I keep the force quit window open because I have to use it all the time. Sometimes I'll do a force quit on everything and restart, sometimes I just force quit the program I want to use and reopen. Sometimes I have to force quit again to get it working.

 

When the magsafe isn't plugged in, I have very few of these kinds of problems. The computer wakes up quickly from sleep and i can immediately log in with my password.

 

Does anyone else have this problem? It took me a long time to realize these other problems seem to be connected with the use of the charger. How safe is Magsafe? Could the magnet be affecting the drive? Could the intake of current be affecting the drive? I don't have any of these kinds of problems with my old aluminum Macbook Pro. That machine is much faster on the internet and I often use it to surf the web instead, though some of the plug-ins are outdated and don't work.

Hmm you can try running the AHT   Using Apple Hardware Test - Apple Support

I would take it in for a assessment even out of warranty you can have a free  'Apple Service Diagnostics' test

Genius reservation http://www.apple.com/retail/geniusbar/

on-line https://getsupport.apple.com/GetproductgroupList.action

check warranty https://selfsolve.apple.com/agreementWarrantyDynamic.do

MacBook Pro (15-inch Mid 2012), OS X El Capitan(10.11.4), i7 480GB SSD 16GB RAM iPhone5 iOS9.3.1, Parallels10.0.2

Have you tried a SMC reset?

https://support.apple.com/en-us/HT201295

Do you have access to another charger to test on your MBP ot another MBP where you can test the charger?

Have you examined the connection of the MBP and the charger for contaminants?

Is there any evidence of discoloration?

The pins on the charger connection are spring loaded.  Do they move freely?

Ciao.