I have decided to create a comparison video showing the start up procedure at both London Victoria (Part 1) and at Brighton (Part 2 starts around 02:59), with the main difference of how much slower the start up procedure on the Class 387 at London Victoria compared with when starting at Brighton. I don't have any issues at the Brighton end but I do when starting from London Victoria. I hope DTG are able to address this issue regarding London Victoria for the PS4. I am not sure if PS5 users are experiencing the same issue.
The difference is clear. I think you might actually be getting better performance than I do in London-Victoria on PS4. Hopefully optimization fixes come soon because it is not really an enjoyable experience to play with the lag I am getting.
Yes, the difference is clear and it is very frustrating not being able to do a complete service to and from London without running into laggy issues.
Can confirm that the performance on PS5 at London Victoria is just as bad. Terrible fps with noticeable lag just like your video. I am playing on the PS5 edition. If I had to take an educated guess; I heard someone report that the 3rd rail incorrectly has collision on BML and you can't walk over it in places, perhaps Victoria has too many collision hit boxes for the console to deal with per frame.
Yeah, there's definitely something weird going on with the third rail. Running across between platforms isn't always as simple as it ought to be, so it wouldn't surprise me at all if that was an issue.