These are the telemetry for one of the laps with VER passing LEC (18th lap):
And this is a few laps later 24th lap:
From there one can say that the slipstream + DRS is indeed still very powerful, in fact quite a lot, VER gets up to almost 327kmh while in a normal lap both would do 301kmh. While LEC instead of hanging around 300kmh chooses to stay in 7th gear and around 285kmh, in fact LEC scrubs off some more speed before the entry down to 282kmh. In video LEC seems to also leave some decent space inside the turn because he's setting himself up to pass VER again the following straight and build some gap in S2 and S3.
Another interesting bit happened at laps 45 and 51 (fastest lap for VER and fastest lap for LEC):
VER's lap was the lap right after his tyre change, LEC after the restart from SC.
It's interesting to see that while LEC is tapering off at end of straight, presumably energy recovery including his fastest lap, for most of the race laps that I checked VER was almost always as sharp as you see up in the graph. I don't know if that's a feature of the Honda engine of course, or they ran it really hard to try and pass, and how it accomplishes energy recovery, but it could be related to them running out of fuel. It's quite a difference in race mode however, it's IMHO cool that FER could still manage to do what they did while tapering off that much on their laps.
LEC really makes the lap up in T6/T7 which he takes full beans, as well as other faster corners like T12 where he simply carries a lot more speed. And this is fast lap on same condition tires for both of them, if anything LEC's tires were a bit colder after the laps behind SC.