Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Slow and inefficient

I bought this drive, in part, because it had U3, so I'm not complaining about that. U3 is moderately useful if you can deal with its shortcomings.What I can't accept is how slow and inefficient this flash drive is. I copied a 207 MB XAMPP folder to the drive which took over 40 minutes and required over 420 MB of space on the drive. Copying the same folder to an external USB hard drive took only 4 minutes and 209 MB of space. So the SanDisk drive is 10 times slower and has more than 100% overhead in this case. SanDisk customer support was useless. They made no attempt to diagnose the problems, which is clearly inherent in the drive. They simply sent a replacement which exhibits the exact same problems.The replacement will be returned.