It wasn't just the map loading, but the engine startup itself was extremely slow compared to earlier versions. I would say it took about 3 times as long to just open the engine itself. My Rescue the Princess level is pretty huge and it never took half as long to load as The Heirs Revenge and no where near the time it takes to run The Heirs Revenge. But I'll be working on converting my game to Game Guru and I'll get a better idea once I get deeper into it.
On a positive note, performance seems to be a big improvement so far. At least from what I saw in The Heirs Revenge anyway. Once I get Rescue the Princess up and running then I'll really have a benchmark to compare against.
System Specs: OS - Windows 7 Home Premium 64-bit SP1, CPU - AMD Phenom II X4 945, 3.0Ghz, RAM - 8Gb DDR3, GFX Card - 2048MB NVIDIA GeForce GT 640, FPSC-R Version - Beta 1.0085