What do you mean, it 'goes extremely slow'? Either a tape plays in it or it doesn't...like, you put a tape in and you see the video and the video looks good or....
As I had to, at one time, maintain VHS and Beta machines, I can offer some tips:
Open the cover and use a can of compress air to blow out any dust and debris.
You will need some denatured isoproply alcohol for the next step, and some cleaning swaps (they are usually made of foam or some other material and NOT cotton swaps like "Q-tips". Q-tips are stranded cotton and if you attempt to clean the heads on a VCR more than likely you will get some cotton strands stuck in the heads.
The "head" or 'heads' are in the large tilted silver wheel/disc. The tape is moved across the heads, and the tilt, along with the spinning heads, causes the track to be laid down diagonally across the tape. Inspect the little rectangular looking protrusions on the cylindrical disk...if you can see any build up of stuff there, gently GENTLY use a swab soaked in ISOPROPLY alcohol (do not use rubbing alcohol as it contains glycerin and that can leave a residue on the heads) and wipe the heads long-wise (not up and down).
Now you can use the alcohol and swab to clean any of the pinch rollers and capstans in the tape path. The small amount of alcohol you use for this won't harm the rubber rollers unless they are already cracked and deteriorated. In that case, ditch the VCR.
Once you get it cleaned (there really are no lubrication points to speak of), then power it up and insert a tape. You can do this before you put the cover back on and you can observe how the tape is extracted from the cassette, and spooled around the head. See if it moves freely and does not bind up or pinch or bunch the tape.
Does the VCR record? If so, does it have two or three speeds available (SP, LP, and EP)?
If you have a prerecorded movie, see how it looks. Note: A standard VCR output on a new flatscreen TV will look absolutely crappy as the VCR does not output hi-def.
if a prerecorded tape doesn't look right, then try adjusting the tracking (usually a button on the remote or front panel).
I have several nice VCRs at home (in AZ) collecting dust. Stereo, high quality units, that I might resurrect with a standard flat screen TUBE tv for my 'museum'
As for rewinding slow, try a different tape. Or take the tape that you have and FF it all the way to the end, then REWIND it. Tape that has been spooled tight for years has a tendency to not want to work right, or if the cassette is wonky, may not work right. I've had to loosen many tapes by FF and RW.
This vcr has been just sitting on a shelf for years and although it does seem to "play" tapes , it goes extremely slow. Spray the whole insides with something maybe or any other ideas to get it back to normal speed? It also seems to fast forward/rewind abnormally slow.