So I already formatted it in Ubuntu Linux which has better disk management options than Windows.
In Ubuntu I did:
-I complately wiped it, meaning complate format, overwriting every block with zeros. That took over 2 hours because even the speed there was 3MB/s slow.
-Tried Different formats, exFAT, FAT32, NTFS, EXT4, still slow.
-When I completely wiped I deleted 100% everything, including partitions, MBR and ETC. and created them again, still slow.
I used this flash drive to boot Ubuntu Live-USB from it when I inserted it computer. I haven’t used it that much, just only booted 4 times. While it still works, It’s still slow.
So the flash drive is worn out right? It says it has 5 year warranty. So I just have to take it to where I bought it and they should replace it with new one, right?
I mean I Also have a Transcend flash drive that is supposed to be not better than this drive and it still is fast as at least 10MB/s and I used it same way as I did on this one, Booting Ubuntu. While I only had that one for few months it works better than SanDisk one I have.