diff --git a/addons/xeh/fnc_preInit.sqf b/addons/xeh/fnc_preInit.sqf
index 3c37cecf8..194621537 100644
--- a/addons/xeh/fnc_preInit.sqf
+++ b/addons/xeh/fnc_preInit.sqf
@@ -73,16 +73,16 @@ GVAR(EventsLowercase) = [];
 
 // generate list of incompatible classes
 GVAR(incompatible) = [] call CBA_fnc_createNamespace;
-
+private _cfgVehicles = configFile >> "CfgVehicles";
 {
-    private _class = configFile >> "CfgVehicles" >> _x;
+    private _class = _cfgVehicles >> _x;
 
     while {isClass _class && {!ISINCOMP(configName _class)}} do {
         SETINCOMP(configName _class);
 
         _class = inheritsFrom _class;
     };
-} forEach ([false, true] call CBA_fnc_supportMonitor);
+} forEach call (uiNamespace getVariable [QGVAR(incompatibleClasses), {[]}]);
 
 // always recompile extended event handlers
 #ifdef DEBUG_MODE_FULL
diff --git a/addons/xeh/fnc_preStart.sqf b/addons/xeh/fnc_preStart.sqf
index 10c4a6362..54ca7adc2 100644
--- a/addons/xeh/fnc_preStart.sqf
+++ b/addons/xeh/fnc_preStart.sqf
@@ -65,4 +65,7 @@ with uiNamespace do {
             diag_log text format ["[XEH]: %1 does not support Extended Event Handlers! Addon: %2", _classname, _addon];
         };
     } forEach (true call CBA_fnc_supportMonitor);
+
+    // cache incompatible classes that are needed in preInit
+    GVAR(incompatibleClasses) = compileFinal str ([false, true] call CBA_fnc_supportMonitor);
 };