Highest level your lotfp game has reached

My campaign started from level 1 and now, after ~ 4 months of play, the long term players have reached level 3 with one or two veterans closing into level 4.
The pace has been quite slow and its mostly because our group is pretty large and we've stuck to the core when it comes to XP (monsters give pitiable amounts, treasure gives lots). So far my players have been very, very careful and have rather kept their lives than risked venturing deep into the dungeons, where most of the treasure is hidden. Their paranoid playstyle was finally rewarded in the Tower of the Stargazer as there were no wandering monsters to drive them away and they didn't fiddle with the traps. Thus they eloped with most of Calcidius' treasure. Clever bastards.

Last session we houseruled that new characters started with as much XP as the party's weakest member, so they won't have to start all from the beginning next time they almost TPK. (Altought, weakest PC only has about 200 xp at the moment, so it's not much. Yet.)
I also let them use Zak's/Jeff's Carouse rules, when they reach big cities. But so far there hasn't been any other short cuts to high levels.
I wouldn't personally mind, if they'd level at faster pace, as I know they will stay clear of the fun stuff (by fun I mean Death Frost Doom), if they consider themselves underpowered. But I cannot force them to get the treasure, so I just have to make do.

Highest I ever reached was level 2 in Petroosh' game about a year ago. (I think someone might've reached level 3, but I was the most skilled PC for a long time.) Petroosh didn't much care about level restrictions and we mostly had to abandon the treasure and run away. My level 2 was a stroke of luck, when the rest of the party died in the chapel room of DFD letting me pilfer all the treasure we'd scrounged.

So far, on our grand tour of LotFP adventures, we've gone through:

The Monolith from Beyond Space and Time (no survivors)
Hammers of the God (well, sort of peeked inside and ran away with a decent profit but it counts)
Forgive Us (this is even more theoretical but I'm still counting it)
Qelong
Death Frost Doom
Tower of the Stargazer
No Salvation for Witches
and pieces of content powered by Weird New World and the Seclusium of Orphone.

The highest level character is level 5. The rest are a level or two behind. We allow a new character to enter play with half their predecessor's XP.

Even at this level I feel like we're definitely playing a high-level campaign. Retainers, crazy boons and items gathered from each adventure and players learning to exploit the summoning rules mean that they made a pretty decisive mockery of most encounters in the last session or two we had before going on a bit of a break.

They also kind of broke the world, but that's been going on for a while now.