Hi Darren,
If I set the simulation to Polygonal, and the max display interval to 1000 it takes almost exactly 4 minutes to simulate on my computer. If I change it to Voxel it’s done in about 20 seconds, but the results are nasty. The results with Polygonal were very good, but it takes longer. But this is to be expected, and is explained in the help file
Something else to watch out for is the simulation accuracy slider. The numbers above are with the slider positioned to the far left (standard). If you slide it to the right, the simulation has the potential for better accuracy, but it will cost you in time. Moving just 2 notches to the right and the polygonal simulation takes 8.5 minutes. If you compare the results you will probably find that the difference doesn’t warrant the extra time. You will have to make that call.
Just to determine how far out (or close) we are to comparing apples to apples, here are my computer specs:

And my system info:
Rhino 7 SR33 2023-9-5 (Rhino 7, 7.33.23248.13001, Git hash:master @ 332dda7497b18e9e6f82f118da5cba0c448151a9)
License type: Commercial, build 2023-09-05
License details: Cloud Zoo
Windows 10 (10.0.19045 SR0.0) or greater (Physical RAM: 32Gb)
Computer platform: DESKTOP
Standard graphics configuration.
Primary display and OpenGL: NVIDIA Quadro P2000 (NVidia) Memory: 5GB, Driver date: 3-28-2023 (M-D-Y). OpenGL Ver: 4.6.0 NVIDIA 528.89
> Accelerated graphics device with 4 adapter port(s)
- Secondary monitor attached to adapter port #0
- Windows Main Display attached to adapter port #1
- Secondary monitor attached to adapter port #2
Secondary graphics devices.
Intel(R) HD Graphics 630 (Intel) Memory: 1GB, Driver date: 6-1-2021 (M-D-Y).
> Integrated graphics device with 3 adapter port(s)
- There are no monitors attached to this device!
OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On
Graphics level being used: OpenGL 4.6 (primary GPU’s maximum)
Anti-alias mode: 8x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: High
Vendor Name: NVIDIA Corporation
Render version: 4.6
Shading Language: 4.60 NVIDIA
Driver Date: 3-28-2023
Driver Version: 31.0.15.2889
Maximum Texture size: 32768 x 32768
Z-Buffer depth: 24 bits
Maximum Viewport size: 32768 x 32768
Total Video Memory: 5 GB
Rhino plugins that do not ship with Rhino
C:\Program Files\Rhino 7\Plug-ins\RhinoCAM 2023 for R7\RhinoArt1FileExporter For Rhino7.0.rhp “RhinoArt1FileExporter”
C:\Rhinoceros 7.0\Plug-ins\AV Plug-ins\AVCommands.rhp “AVCommands” 0.1.8651.19964
C:\Program Files\Rhino 7\Plug-ins\RhinoCAM 2023 for R7\RhinoCAM 2023 For Rhino7.0.rhp “RhinoCAM 2023 - The cutting edge CAM plug-in for Rhino 7.0 from MecSoft Corporation”
C:\Users\dan\AppData\Roaming\McNeel\Rhinoceros\packages\7.0\NVIDIADenoiser\0.4.3\NVIDIADenoiser.Windows.rhp “NVIDIADenoiser.Windows” 0.4.3.0
Rhino plugins that ship with Rhino
C:\Program Files\Rhino 7\Plug-ins\Commands.rhp “Commands” 7.33.23248.13001
C:\Program Files\Rhino 7\Plug-ins\WebBrowser.rhp “WebBrowser”
C:\Program Files\Rhino 7\Plug-ins\rdk.rhp “Renderer Development Kit”
C:\Program Files\Rhino 7\Plug-ins\RPC.rhp “RPC”
C:\Program Files\Rhino 7\Plug-ins\AnimationTools.rhp “AnimationTools”
C:\Program Files\Rhino 7\Plug-ins\RhinoRenderCycles.rhp “Rhino Render” 7.33.23248.13001
C:\Program Files\Rhino 7\Plug-ins\RhinoRender.rhp “Legacy Rhino Render”
C:\Program Files\Rhino 7\Plug-ins\rdk_etoui.rhp “RDK_EtoUI” 7.33.23248.13001
C:\Program Files\Rhino 7\Plug-ins\rdk_ui.rhp “Renderer Development Kit UI”
C:\Program Files\Rhino 7\Plug-ins\NamedSnapshots.rhp “Snapshots”
C:\Program Files\Rhino 7\Plug-ins\IronPython\RhinoDLR_Python.rhp “IronPython” 7.33.23248.13001
C:\Program Files\Rhino 7\Plug-ins\Calc.rhp “Calc”
C:\Program Files\Rhino 7\Plug-ins\RhinoCycles.rhp “RhinoCycles” 7.33.23248.13001
C:\Program Files\Rhino 7\Plug-ins\Toolbars\Toolbars.rhp “Toolbars” 7.33.23248.13001
C:\Program Files\Rhino 7\Plug-ins\3dxrhino.rhp “3Dconnexion 3D Mouse”
C:\Program Files\Rhino 7\Plug-ins\Displacement.rhp “Displacement”
If you are interested in saving time on the machine and improving the surface finish at the bottom of the 2 pockets I would suggest using an endmill for the vertical walls and the floor. You could use a containment curve to stop the planar path from dropping into the pockets. But that’s a discussion you didn’t ask for. 
I hope this helps.
Dan