:celebration: Thanks for suggestions, but it seems that I have found a better solution! And also have some recommendation for all newcomers into this great game (valid also in Fallout: New Vegas!).
Whoever wants to cheat should first visit site http://fallout.wikia.com/wiki/Gamebryo_console_commands.html
Gamebryo company was involved in creating game engine, and the console was left as a debugging and quality assurance tool, but it also can be (and often is) used for cheating purposes. As so many of you already know, console is accessed by hitting ~ key (1st on the left under Esc key). Now, among many useful commands that can enhance player character's abilities (by changing S.P.E.C.I.A.L. stats and all skills and many other things, there are some that I used to my great satisfaction:
1) "player.modav speedmult (percentage)
-as percentage I've set 40; and yes, that command is far better than "setgs fmoverunmult /multiplier), 'cause this one can caue numerous bugs (for it means: set game settings forward move run multiplier), and game settings are not something to be mess around if you 're unsure about the outcome;
- this way I increased my character's speed, even when sneaking - but then be careful when running down the slope or jumping down - injuries are more than probable! (By the way, all injuries that player character (or PC) sustain are easily fixed with yet another console command: "player.resethealth" - console magic in action!)
2) "set timescale to (scale)" where "scale" is number that reflect ratio between ingame and real-world time. Default value is 30, meaning 1 hour in real time actually refers to 60x60x30=108300 s = 1 day+6h of time in game! Setting down that number to 1 - or near 1, positively under or near 10, AND having your character at the same time accelerated greatly improves chances to do more things within 1 ingame day! For instance, with that settings my character had started, and is close to finishing, 3 quests, and already perform 2 or 4 technology transactions with Protector Casdin of the Outcasts, + ThreeDog have been accurately informing of Lone Wanderer's achievements and karma progress!
So far, this setting suit me great. later I may even try out setgs fmoverunmult 40!
So much on this occasion from deep and dark place where Hades rules!
Greetz to all you guys&gals!

The problem with messing around with the timescale is that it doesn't change how fast things respawn. That means that while you're running around super-fast and time is going super-slow, enemies and shop inventories are not being refreshed. You could come to the point where theres nothing left to kill and nobody with anything to sell.

Personally I use a mod called "Immersive Timescale", which changes the time based on where you are. If you're indoors time moves more close to real time, but if you're travelling cross-country you can expect it to take a few days of travel to go from one edge of the map to the other. I rather like this and it's completely compatible with all Needs/hardcoe mods. With this mod I don't have to worry about taking 3 in-game days to clear out a mansion, but also don't have to worry about beating the entire game within 1 game-week.