Mathematica execution-time bug: symbol names

Question

There is a strange bug that has been in Mathematica for years, at least since version 5.1, and persisting through version 7.

---

Module[{f, L}, L = f[];
  Do[L         


        

Answer 1

As to version 8: I tried 100,000 random strings of various lengths and didn't find anything out of the ordinary.

chars = StringCases[CharacterRange["A", "z"], WordCharacter] //Flatten;
res = Table[
       ToExpression[
        StringReplace[
         "First[AbsoluteTiming[Module[{weirdness,L},L=weirdness[];\
    \[IndentingNewLine]Do[L=weirdness[L,i],{i,10^4}]]]]", 
         "weirdness" -> 
          StringJoin[
           RandomChoice[chars, RandomInteger[{1, 20}]]]]], {100000}];