Very slowly and USB OTG with loose contact

Unfortunately this connection is very very slow with me.
Both Samsung SDHC card (MB-SSBGBFFP 32GB) are Class 6 card and should write at least 6MB / s and 24MB / s read.
Reviews to the cards usually show + 7MB / s write.

Unfortunately, I reach with this stick only constant 1.6MB / s regardless of whether smaller MP3s (3-5 MB per file) or even large data (+ 2GB).
It also makes no difference whether the card with NTFS, FAT32 or exFAT formatted.
Have been doing all USB 2.0 and USB 3.0 ports on the PC tested.

Also, I have to test problems USB OTG as this stick probably has a loose connection.
Because when connected to the mobile phone (Samsung Galaxy S3), until nothing is detected, if you then easily move the stick, it will be recognized suddenly.
Unfortunately, the use is thus rather impossible.