My understanding was that a retainer or cage for bearings simply allows you to use less bearings -- otherwise typically the bearings fill the cup and are all to

My understanding was that a retainer or cage for bearings simply allows you to use less bearings -- otherwise typically the bearings fill the cup and are all touching. In other words I'm not sure I even buy the premise... Also the grease used also has a huge impact on the speed of the bearings (for example a really light grease is fast while the heavy stuff is reserved for conditions that demand it)