I find LGW security to be anything but efficient. This is just my opinion, but I have seen much better.
For starters, the clerks telling you which line to go in, will often direct you to a line which has a massive queue down it.
Secondly, if you want to opt-out of the body scanners, most staff will deny the existence of an opt-out until the manager comes along and tells you that an opt-out is allowed. They then seem to take as long as they possible can to search your every possession.
Finally, have you seen what it looks like at peak time? They don't open all of the lanes, but the lines back up further than the passport gates! It's a nightmare compared to BSL and DUS.
If you are from the USA, you might like not having to remove your shoes, or maybe the fact that the joke called "TSA" doesn't run it, so that is a good start. For such a developed country, USA security reminds me of security in a third-world country.
The only checkpoint that is worse than it, is LHR T5. There is a whole thread entitled "T5 security is a nightmare!", or something like that. Anyway, each to his/her own, I suppose.