The slow down is CPU over load and at this point, a known issue. If you do a Ctrl - C, you'll see the graphic. It will be the purple bar. This video gives a quick over view It is one of the reasons i've been starting to look at upgrading.
LGC is hosting the final race of the GPLaps Historic Road Racing Championship next week. It's an excellent series. You can join in the preQuali week this coming monday-friday, with the race on saturday (there will be a broadcast). Check the series rulebook for info and signup instructions: https://docs.google.com/document/d/1TN0nLNfk3brLQVAXJml5aAePXU0iPsE6lzliACATcmo/edit
UPDATE! v0.86 on the Workshop! http://steamcommunity.com/sharedfiles/filedetails/?id=1213606756 - New AIW file (fixes old Tertre Rouge online bunny hop, T1 track cut warnings, and added 104 paddock/grid support) - AI don't crash in the paddock anymore (thanks to svictor) - Prac/Quali pit speed limit down to 160kph (to reduce prac/quali pit accident chance) - Race speed limit 370kph - Narrowed some AI corridors to reduced the chances of AI crashing while trying to pass/two-wide/three-wide - League-Friendly version added with all hay bales changed to static, and anti-cut hay bales in some corners. - Easy pit re-request if the car drifts out of pit road before pitting (long xpitin mesh) - Moved ambient reflection probe (brighter, and removed mild green tint). - Basic track surface PBR added - PBR for many buildings, props (including psuedo-retro-reflective markers) - Many general texture tweaks - Slight improvements to cameras and added ambient crowd/announcer sounds. - Added pit entry horn to reduce chance of a t-bone on pit road while exiting paddock (yes, there is an air horn model on the pit building) - Added trackside reflectors for Golf Course kinks. Known Issues: - AI with some car types (fast with low grip / historics) may struggle to take the fast corners as quickly as a human driver. - AI may fail to avoid other cars in the pits (rear-ending a slower cars instead of slowing down) which can cause pitlane pile ups in prac/quali/race.
For flighty cars like Howston I always had same work around with large fields. Fixed Setup Full Tanks Fuel x 0 Tyres 4-5 x Stops for tyres only so time matches AI and stagger your stops. Lower aggression Full tanks makes some ISI cars more predictable and stable. Personally I think it's way obvious. AI have more grip and slide less all race long. In pits when hit they are always heavy and harder to budge It's called Dynamics The downside is you don't get that extra feeling as fuel comes off but I think the upsides outweigh this. Tip: If you think a car tries to take your spot or drive through it just hold the brakes at 100% Same thing if you get rear ended at turn, 100% throttle and 100% brakes then easing off the throttle. Get rear ended easy to make the deadly mistake and lift off instead.
Tried it and looked really nice in VR, although I was upside down most of the time with a McLaren M1C that seemed intent not to stay straight :-D
