Solved

No overheating when not watching the race

This is linked to a post about running no-setup being faster.

I've noticed that in races I actually watch, my tyres overheat meaning I have to back off, making me go slower. In races i don't watch, my driver's are at a constant push level (standard). In the races where I don't watch it, my driver's are able to stay at a relatively consistent and fast pace. This suggests that when you arent controlling the drivers the game isn't taking into account the tyre temperature, meaning you can go faster for longer.

This was clear in my last 2 races. (https://igpmanager.com/app/p=league&id=3793)
In Europe, I joined the race for the entire first stint, and my tyres started overheating after a few laps and I could no longer keep up with the leaders. In Turkey, Britain, Germany and Belgium however, I didn't watch the race at all, and I won them.

This also links to the setup bug, because at the start of the season I changed my setups and strategies, and I didn't do well. In China (custom setup, strategy, and watching the race) I was P20 and P30, the next race, Bahrain (stock setup, strategy, not watching), I was P2 and P10. That's a massive jump, which no car development can cause.

Hopefully you can look into it, thanks :)

In regards to your tyres overheating, you need to use a lower push level or you need to run tyres that don't overheat in relation to the track temp.

This likely doesn't have anything to do with your lack of a set up, or very little at all.

And if you aren't watching the race, how do you know your tyres aren't overheating?

Josh probably looked at the lap times afterwards. If you look at any team who used the default tyres and setup, you will notice that they have very consistent lap times. I've just looked at a few and those races where mediums and neutral should have overheated were still consistent with no obvious tail off.