Upgraded graphics card to a NVIDIA GTX 1050 (2G DDR5) which made all the difference.
If your rig won't reach 60fps constantly the game will run slow (not choppy but slow) because every frame is rendered. No frames are dropped. So for example if the machine averages 50 FPS -> an ingame second will last for 6/5 seconds.
My CPU is bored but Daytona wants a good graphics card.
I'm happy with the GTX1050. Adequate performance, not too loud, needs "only" 75 watts max.
Wouldn't want an overheating loud card in my Sega race cab...
10 thumbsup to Howard!
Lots of thumbs up for everyone being helpful in this thread!
And a well deserved thousand thumbs up for the gods of racing: SEGA.
Here's a pic of the project cab. Quite a bastard isn't it?