USHPA proposes:

The US Hang Gliding and Paragliding Association proposes that the
number of hang glider pilots in any Category 1 event be limited to 100.

There was a lot of concern at the worlds in Brasilia in August surrounding the
number of pilots at Category 1 competitions. The discussion and consensus among
many was that 150 is just too many for a safe competition. Although there could
be locations where allowing 150 pilots is safe, in most places it is simply
unsafe and makes for a less satisfying competition.

Obviously, the downside to cutting the maximum number down to 120 is that
organizers cannot get sufficient sponsorship to make a Category 1 event
financially viable. For the upcoming hang gliding worlds in Italy, the
organizers have reasonable sponsorship, so it isn't likely to be an issue there.
For future Category 1 competitions, organizers would be made aware of this rule
well in advance of putting in bids and could plan for less income from entry
fees.

http://www.fai.org/page/civl-meetings