I am aware of some of the reasons why OCaml classes and objects are slower than records. The lack of nominal subtyping makes determining memory layout at compile time much more difficult. While I am also curious why "nice cases" of objects/classes couldn't be optimized (perhaps some link time check), when most of the objects adhere to a nice hierarchy, I would like to defer that discussion until another time. For now, my primary question is: Just *how* slow are objects/classes? Has there been any relevant benchmarking efforts that could shed some light on this? For example, how much more expensive in terms of memory are objects (compared to records). How much slower are property accesses and method invocations than record accesses and module function invocations? Jordan