JGCRI
Severe runtime difference between Windows 11 and WSL on same machine
Description: I observed a large difference in runtime performance in GCAM v8.2 when running the reference scenario on the same machine under two different environments: native Windows 11 vs. WSL (Ubuntu).
System details:
- Hardware: [12th Gen Intel (R) Core(TM) i7-12700H, 32GB]
- OS: Windows 11 (24H2)
- WSL: Ubuntu [24.04.2 LTS] running inside Windows 11
Observed behavior: On Windows 11 (native run):
Data Readin & Initial Model Run Time: 2507.27 seconds.
Data Readin, Model Run & Write Time: 5255.66 seconds.
On WSL (same machine, same scenario):
Data Readin & Initial Model Run Time: 449.001 seconds.
Data Readin, Model Run & Write Time: 756.081 seconds.
Expected behavior: I expected comparable performance across Windows 11 and WSL since both runs are on the same hardware. Instead, runtime on Windows is more than 6× slower for the initial model run and ~7× slower for the full run.
Additional context: Both runs used the same model version, scenario inputs, and machine. The only difference was the execution environment (Windows native vs. WSL). I also described the method I compiled GCAM v8.2 in WSL here
2025-08-20 Tested configuration
- Execution folder: C:\gcam-v8.2-Windows-Release-Package\
- Windows Search indexing disabled for this folder
- Verified that Windows Defender real-time protection and OneDrive/other sync services are not affecting the run
I changed the path of GCAM and turned off the indexing but didn't work
Data Readin & Initial Model Run Time: 2645.37 seconds.
Data Readin, Model Run & Write Time: 5180.61 seconds.