RPI 3 weak onboard wifi


I’m using my RPI 3 with OSMC (Kodi 17 Krypton). SSH is really slow, weather hangs often and when I synchronize the database it takes serveral starts because it says in the middle “no connection to the movie database”.
When I look at my router the RP3 has a very weak wifi rate. (5 / 8 Mbits/s) my notebook in the same room has 52 / 86 Mbit/s.

What I wanted to try now is using a wifi USB dongle (that I can position better with a usb extension cable) and deactivae the interal wifi. Is that a good idea? How do I do this with OSMC?

Thanks in advance

Disabling onboard wifi on the Pi3 has been covered extensively on the forum, please try the search facility.

Thanks. I did dtoverlay=sdhost in /boot/config.txt and plugged in a USB wifi dongle. Now the connection is nice.

Is this a known issue that de onboard wifi is weak? or is is due to the positioning of my pi?