Hi.

Well, what do you know... CollectionProduct may be improved...

Profiler measure: [(1*20) * (2*19) * (3*18) * (4*17) * (5*16) * (6*15) *
(7*14) * (8*13) * (9*12) * (10*11)] 579mus 833ns 

Profiler measure: [((1*20) * (2*19)) * ((3*18) * (4*17)) * ((5*16) *
(6*15)) * ((7*14) * (8*13)) * ((9*12) * (10*11))] 462mus 585ns 

Profiler measure: [(((1*20) * (2*19)) * ((3*18) * (4*17))) * (((5*16) *
(6*15)) * ((7*14) * (8*13))) * (((9*12) * (10*11)))] 380mus 493ns 

Profiler measure: [((((1*20) * (2*19)) * ((3*18) * (4*17))) * (((5*16) *
(6*15)) * ((7*14) * (8*13)))) * (((9*12) * (10*11)))] 367mus 248ns 

The best time for regular grouping was greater than 380mus...

Andres.