Actually opposite is true. 

Heavier putters slow you down on fast greens and vice versa. Try it yourself. 

Thanks for the input, Kurt!!  Now that you mention it, I can recall a few instances where my heavy putter seemed to perform better on faster-paced putts.

I am going to go against the grain on this one....I prefer heavier putters on slower greens since the physics give the ball more pace vs. on fast greens lighter putters do not role the ball as far with the same amount of effort...however I can see where someone may prefer the opposite for feel.  That being said, among better players at my club the consensus is that lighter putters are better for fast greens... JAT, sorry to confuse the issue but I would consider trying both and see what works best for you... 

GolfMachine,

I ran into a similar situation, but opposite view.  My SC came with 15g weights and I wanted a heavier feel from the putter head.  I swapped out the 15's for the 25's and I am much happier with the feel.  I can say that our greens typically run between 9-11 on the STIMP.

Regardless of where I play, I always try and work on getting the speed of the greens as soon as I get to the course.  This has been helpful for me, but your point about faster or slower greens and the associated weights has truly never entered my mind.

Good luck on finding out what works best for you and let us know what you end up deciding to do.

And.....I'll go against the grain even further by insisting that it's what YOU feel, and what you expect from your putter.  Case in point, the heavy putter on fast greens to ME means, less pull back and follow through which keeps me on target with the line (smooth as silk).  A fast putter for ME on fast greens works in the opposite way (bulky, second guessing the speed, pull back etc.).  It's weird I know, but trust me....it's a "FEEL" thing.  Try it yourself!!

GolfMachine,

I think before you look at the weight, you should also consider the shaft length and grip.  If you have a 33" putter, 25 grams would be 'heavier' than the original Scotty, but not too much so.  If you have 25 grams on a 35" putter with a Pistolero grip, I agree that would probably be 'too' heavy.

The feel question is totally up to you.  My own pro helped me a ton when I was having trouble putting on faster greens.  We had just switched from Bent to Ultradwarf and our stimps in the summer went from 9-10 to 11 and up for tourneys.  I had previously cut my putter down and added a mid size grip.  The two changes took the swing weight from D5 to C0.  This was much too light for me and my pro suggested at least D0.  Lead tape and a lighter grip brought the putter back up to D0 and I've been much happier there.

Good luck!