Why does upload the firmwaer with the typeC is very slowly?

Hi,everybody!
I use OSX to compile and upload the firmware for PX4.But the uploading process is extremely slow while I use my new Macbook’s type C and USB3.0 adapter.(it takes about 3 mins to finish the job) Since my old Mac never upload slowly like this.It should be something wrong.How can I fix it?any suggestion will be appreciated!Thank you!