Below are some performance optimizations tips for WebKitX:

• Avoid instantiating multiple WebKitX controls at the same time. For every browser instance, WebKitX launches several CEF3XClient.exe sub-processes necessary by Chromium architecture. Those sub-processes burden your system's resources. You can control WebKitX instantiation by setting the DealyedBrowserCreation property to true and explicitly create or destroy WebKitX control by calling WebKitX.Create and WebKitX.Destroy methods respectively.
• Handle OnCreate event and define a cache_path to a folder with read and write permissions.
• If using multiple WebKitX controls, handle OnCreate event and assign to each control a different cache_path; sharing the cache decreases performance.
• If using persistent storage and cookies, handle OnCreate event and define persist_session_cookies and persist_user_preferences flags as well as user_data_path.
• Disable navigation control by handling OnCreate event and setting disable_on_before_navigate_event to true.
• Using content filtering decreases performance. However, it is disabled by default.
• Unless you need to synchronously respond to events, it is highly recommended to use an asynchronous model. Handle OnCreate event and set asynchronous_com_events to true.
• We recommend disabling legacy Internet Explorer feature window.status by handling OnCreate event hand setting simulate_ie_window_status to false.
• We recommend diabling remote debugging by handling OnCreate event and setting remote_debugging_port to zero.
• If you still have performance issues, use GetPerformanceCounters method to see which resources cause delays.
• Ultimately you can use ShowDevTools to gain full access to Network, Rendering and Script latencies.

OnCreate switches the boost performance:

Private Sub Editor_OnCreate(ByVal Settings As WebKitXCEF3Lib.ISettings, CommandLineSwitches As String)
    
    On Error Resume Next
      
    With Settings
        
        .app_path = FS.GetAbsolutePathName(App.Path)

        .accept_language_list = "es-CL,en-GB"
        .persist_session_cookies = 0
        .persist_user_preferences = 0
        .show_context_menu = False
        .asynchronous_com_events = True      
            
    End With
    
    CommandLineSwitches = CommandLineSwitches + " --no-proxy-server --disable-cache --disable-gpu-program-cache --disable-gpu-shader-disk-cache"
    CommandLineSwitches = CommandLineSwitches + " --disable-background-networking --disable-background-timer-throttling --disable-backgrounding-occluded-windows"
    CommandLineSwitches = CommandLineSwitches + " --disable-breakpad --disable-client-side-phishing-detection --disable-default-apps --disable-dev-shm-usage "
    CommandLineSwitches = CommandLineSwitches + " --disable-renderer-backgrounding --disable-sync --metrics-recording-only --no-first-run --no-default-browser-check"
    
End Sub