CMake-ide slow on large projects

[ideasman42]

I've found cmake-ide becomes quite slow (near unusable ~4-5 second load times for any source file - using fairly modern PC).

From enabling debug-on-exit and pressing C-g when its hanging, it seems this is caused by parsing a large json string (compile_commands.json is 3.2mb, 10,194 lines).

Debugger entered--Lisp error: (quit)
  json-read-string()
  json-read-object()
  apply(json-read-object nil)
  json-read()
  json-read-array()
  apply(json-read-array nil)
  json-read()
  json-read-from-string("... REDACTED, 3.2MB JSON ...")
  cmake-ide--cdb-json-file-to-idb()
  cmake-ide--on-cmake-finished()
  cmake-ide-maybe-run-cmake()
  run-hooks(find-file-hook)
  after-find-file(nil t)
  find-file-noselect-1(#<buffer creator.c> "/src/blender/source/creator/creator.c" nil nil "/src/blender/source/creator/creator.c" (6427826 2049))

[ideasman42]

Should have checked second page, duplicate of #19