How could this effect the Russian performance in the future ww1?
They'd likely be more organized and possibly they'd be similar to the British Army in that the war would remain in the Russian consciousness when war hits. It really all depends on how much the Russian General Staff chooses to really study the tactics of it. They could learn valuable lessons or just as easily brush it off, it really all depends. If they absorb the information and incorporate it into tactics, it could allow them to be much more successful in an alt-WW1. Instead of disasters like Masurian Lakes, we could see a tentative deployment of tactics similar to those used in the Brusilov Offensive.
The loss of the Russian fleets was in my opinion enough of a loss of prestige to make thebAnglo Russian convention plausible. From memory it moved Russia from having the second or third largest fleet in the world to 7th.
For Britain Russia was no longer as scary at this stage.
This different Russo-Japanese War wouldn't have the disasters the Russian's faced at Port Arthur and Tsushima particularly. The Russian fleet would likely stay in port, and if Port Arthur never falls to Japanese forces, the Russian Fleet would have no reason to move out (they'd employ a Fleet-in-Being strategy.) Without the loss of the Russian fleet, in addition to the massive annexation of Manchuria (and possibly Korea) would generate enough Russophobia in the Raj to keep the Great Game rivalry going.