Most direct & quickest route from Prague to Linz, Austria

There are no "high speed" trains in Czech Republic. There are a couple for direct trains that do it in 4 hours, one at 6:01 in the morning.

CK Shuttle offers a few options. No idea about price. We used their services for a shorter Cesky Krumlov to Linz trip and it was excellent.

I can't speak to train service but as mentioned up thread, we plan to use CK shuttle for two shared transfers on an upcoming trip. Our choice was based on recommendations for convenience, comfort and door to door service. www.ckshuttle.cz.

There is a direct train Prague Linz as already mentioned above. Shuttle to Linz is justifiable if you stop in Cesky Krumlov. Czech Republics is a small country and distances are short. Main rail lines were fixed after fall of communism. Now these rail lines are called corridors and trains can go up to 160 km/h = 100 miles/hour. I would not say that is slow but neither is superfast like in some other countries of Europe where trains can go 200 to 300 km/h. But there are different requirements for tracks for these superfast trains. That would be much more expensive than tracks for 160 km/h and not economical in saved time on short distances of C.R.

If you have not found the direct trains in your schedule search, it may be date dependent - they're not shown as running between August 9 and 18 this year.

trains can go up to 160 km/h = 100 miles/hour. I would not say that is slow

Not particularly fast though. The all-stops commuter trains on the line I used to work on run at 110 mph (177 kph). The ones near where I live do 125 mph (201 kph), on Victorian era routes.

Nevertheless, I'm sure that the Czech trains are considerably less expensive.

Thanks all for your replies. I will check it out!