Enhanced Security hinders performance of WASM applications (Including Blazor)

Your Blazor WebAssembly slowdown under policy-enforced Edge Enhanced Security matches Microsoft’s documented behavior. Enhanced Security runs WebAssembly through an interpreter, which Microsoft warns might not provide expected performance; this is a security tradeoff, not a Blazor configuration fault.

First, review applied policies and record EnhanceSecurityMode, EnhanceSecurityModeAllowUserBypass, and JavaScript JIT policies. If policy controls the setting and user bypass is disabled, the user cannot correct it locally. Ask the Edge administrator to add the application’s domain to EnhanceSecurityModeBypassListDomains, refresh policy, restart Edge, and retest. If DefaultJavaScriptJitSetting also blocks JIT, the administrator should review JavaScriptJitAllowedForSites; its exceptions operate at registrable-domain granularity and apply separately to embedded frames. Avoid disabling Enhanced Security globally unless the organization accepts that reduced protection. If domain exceptions are prohibited, Microsoft documents no client-side Blazor setting that restores JIT performance. Capture the Edge version, applied policies, and a performance trace, then open a Microsoft support case.