Double Switch has a fixed time limit, so as long as you skip the few required cutscenes(Eddie's intro) and quickly move to the next act, the actual speed should not be an issue.
The real challenge is catching as many intruders as possible. Act 1 and 3 are fairly linear, and just require quick reflexes, but most of the targets appear in a fixed order, so long as you keep tabs on the room icons for when someone is arriving. With enough practice, you'll get a feel for which intruders are going to trigger a trap almost immediately(anyone by the window in Alex's room, anyone approaching Punch in Brutus'), or taking their sweet time(Luigi approaching the Totter trap in the Grads' room, the blonde intruder at the elevator in the basement), and which ones you absolutely must catch right away: Eddie's attacks, the Mummy rescues/traps, the Handyman unlocking new traps, and anyone going for the powerbox, phonelines, or the Society leader going into the basement(he shows up very fast, and is introduced by an ominous music cue).
Act 1 and 3 have few intruders, and are both really quick, but Act 2 is where RNG will make or break a run, as it's longer than 1 and 3 combined(and has most of the intruders in the game). Many intruders appear within split seconds of key events(trap unlocks, mandatory rescues), and you'll have to decide on very short notice if they're able to be captured or not. If it's too close to call, forget it, and go after the mandatory event. Some events are designed to always be possible(saving the band from the intruder, you do have time for that Brutus trap JUST before it), some are really up to RNG(saving people from the mummy).
The most aggravating delays are usually the blonde with the fan in the lobby(she always triggers it the second time, not the first), Luigi at the Lamp in the Band, Luigi at the teeter-totter in the Grads(he 'fakes' an approach to the Coffin), and the blonde at the elevator in the basement. Sometimes the intruder in Alex's room takes his time getting to the Fireplace, so sometimes you have time for an event before he reaches the trigger.
