Unfortunately, ADB plugin for TC requires debbuging enabled to function. I doubt it'll make a difference, but I'll try it with WExplorer in MTP mode.
Well, USB debbuging made no difference, but MTP mode reached 8-9 MB (better, but still way below what it should be), while ADB+TC says it creeps at ~3 MB.
Same file copied via MTP needs 3.5 mins and ADB plugin requires for stumping 16 minutes! And that's on extSD, not internal. So, ok, the TC plugin is a decomposing cadaver, fine, but that doesn't account for MTP's speed.