I can test things. What are you looking for especially?
I used your plugin on my vam installation with ~10k vars. Normal startup time is 23 secs, with your plugin 18 secs.
AMD Ryzen 7 9800X3D
ASUS ROG STRIX B650E-F GAMING WIFI
ZOTAC GeForce RTX 5090 SOLID OC 32GB
64GB DDR5-6000/CL30 Kingston FURY Beast
2TB WD Blue SN580 NVMe
[Info : BepInEx] Loading [VaM LeanCore 0.7.0]
[Info :VaM LeanCore] VaM LeanCore 0.7.0 loaded. Morph demand loading, parallel package JSON preparation, and fast package indexing are active when the master switch is enabled. No game assemblies are replaced.
[Message: BepInEx] Chainloader startup complete
[Info :VaM LeanCore] Package index refresh hook entered.
[Info :VaM LeanCore] Package index preparation started on first VAR scan.
[Info :VaM LeanCore] Checking package index at BepInEx\cache\VaMLeanCore\package-index-v1.bin.
[Info :VaM LeanCore] Validated package index with 9973 archives.
[Info :VaM LeanCore] Package index preparation completed; cache-usable=True, capture-run=False.
[Info :VaM LeanCore] Fast package file-entry factory initialized.
[Info :VaM LeanCore] Fast package file-entry factory matched VaM's constructor field-for-field.
[Info :VaM LeanCore] Package index: hits=9945, misses=0, bypasses=28, hydrate-ms=1201.9, lazy-zip-opens=0.
[Info :VaM LeanCore] Parallel package JSON preparation skipped because VaM caching is disabled.
[Info :VaM LeanCore] Deferred global package JSON cache sweep #1; prepared cache files will parse through VaM on first use.
[Info :VaM LeanCore] Deferred global package JSON cache sweep #2; prepared cache files will parse through VaM on first use.
[Info :VaM LeanCore] Package JSON demand cache: skipped-sweeps=2, loaded-packages=6204, total-ms=0.7, slowest-ms=0.0, slowest=GilgameshVR.Lara.1.