Out C# code invokers FNP_checkout function from lmgract.dll to checkout license, refer below code lines: [DllImport("lmgract.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)] private static extern ReturnValues FNP_checkout(String FeatureName, String FeatureVersion, int NumberOfLicenses); public enum ReturnValues { [Description("Success")] success = 0, [Description("Routine failed")] failed = 1, [Description("Invalid handler")] jobhandleNull = 2, [Description("Null pointer")] pointerNull = 3 } On same PC with dual boot, the checkout speed is good with Windows 10, around a couple of 100mS. However, the checkout time will be at 30 seconds range with Windows 7. During license checkout, there will be a process running with high CPU priority, which will fully occupy several CPU logical cores, and the overall CPU usage will be around 25% ~ 30%. If such process is not running, slow license checkout time with Windows 7 will not be observed. Any suggestions to speed up license checkout on Windows 7 configuration with a busy process consuming ~25% CPU process time? We've already avoid our client code from using those fully occupied cores by setting CPU affinity. The only thing seems to make difference is to low down the busy process's priority from high to low.  Thanks. ... View more