Train from Paris to Switzerland - timing for security/customs

No customs or security, but TGV wants you on the train 5 minutes before departure. So if you arrive at the 30 minutes before departure, you should be OK. Gare de Lyon is huge and there are 2 separate sets of platforms and will take a few minutes to get oriented and locate which section of the station to go to for your train.
http://parisbytrain.com/gare-de-lyon-photos/

Actually we took train (Thalys) from Paris to Amsterdam about a month ago.. and we did have to put our bags through an xray.. .I do not recall doing that before for that train.. only ever for Eurostar..
This took very little extra time however.. they didn't check id or anything.. we were just funnelled into two lines right on the platform where xray machines were set up ..

I agree 30 minutes would be sufficient.. but would likely allow myself about 40 minutes , because I always pick up a snack at train station to eat onboard.

ryan,

As the others have mentioned, that's not an "international" rail trip. Just board the train in Paris as you would any other and in a few hours you'll arrive at Basel SBB. If you're going to the Lauterbrunnen Valley once you arrive in Interlaken, you'll need to disembark at Interlaken Ost, which should be the second stop.

Thalys introduced security screenings after the attempted mass shooting on a train last year. I think Lyria still has no security screenings.

What I found interesting about the Thalys train is that the security was only on the Paris end. There was no security when leaving Amsterdam.

There is no security leaving Amsterdam but there are often drug dogs and agents at the Paris end when it comes in.