Failing external hard drive

Hello all,

I'm kinda freaking out at the moment. I have a WD elements 1tb external hard drive and it was working fine until a couple of days ago. I was trying to get all of my photo's an video's off it to get back up and upload to cloud, So I start to transfer the files but it wasn't going at normal speed, so i cancelled restarted computer and all i got after I put in password was a flickering desktop... So restart again, good so far, when i open explorer to go to map everything turns black after a few seconds. I restart again without my WD connected and everything works fine. This is where i start to freak out. There is about 350 GB of very important data on it i can't lose. (My previous back up drive crashed a while ago and haven't had the time to make another one also because of the Nas we were going to buy) So I try connecting it to my laptop with succes and a lot of patience. Now trying to transfer single maps at a time it takes about 3 to 5 hours for around 250 mb. So i was looking for another solution and a friend came to help with a data recovery program which is now running but again very very slow (about 10% now from 261 mb and already busy for 40min).
I've also tried a repair off the drive and that failed due to snapshot error, did offline scan and repair but didn't help.
Is there anyone that can tell me something else to try, that can help me get the needed data off faster without losing it?
Any help would be greatly appreciated, Thank you