Question

I wrote a simple function to retrieve system information using the WMI, passing as parameter the class and the property name. when I execute the function like this

  Writeln('Procesor Id '+GetWMIInfo('Win32_Processor','Name'));
  Writeln('Mother Board Serial '+GetWMIInfo('Win32_BaseBoard','SerialNumber'));
  Writeln('BIOS Version '+GetWMIInfo('Win32_BIOS','Version'));

The execution time is about 1300 ms.

I need retrieve a lot of additional information, So Is possible reduce the time of execution of this function?

This is a sample application with the function

{$APPTYPE CONSOLE}

uses
  Diagnostics,
  SysUtils,
  ActiveX,
  ComObj,
  Variants;

function  GetWMIInfo(const WMIClass, WMIProperty:string): string;
var
  sWbemLocator  : OLEVariant;
  sWMIService   : OLEVariant;
  sWbemObjectSet: OLEVariant;
  sWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  Result:='';
  sWbemLocator  := CreateOleObject('WbemScripting.SWbemLocator');
  sWMIService   := sWbemLocator.ConnectServer('', 'root\CIMV2', '', '');
  sWbemObjectSet:= sWMIService.ExecQuery('SELECT * FROM '+WMIClass,'WQL');
  oEnum         := IUnknown(sWbemObjectSet._NewEnum) as IEnumVariant;
  if oEnum.Next(1, sWbemObject, iValue) = 0 then
    Result:=sWbemObject.Properties_.Item(WMIProperty).Value;
end;

var
 SW : TStopwatch;

begin
 try
    CoInitialize(nil);
    try
      SW.Reset;
      SW.Start;
      Writeln('Procesor Id '+GetWMIInfo('Win32_Processor','Name'));
      Writeln('Mother Board Serial '+GetWMIInfo('Win32_BaseBoard','SerialNumber'));
      Writeln('BIOS Version '+GetWMIInfo('Win32_BIOS','Version'));
      SW.Stop;
      Writeln('Elapsed ms '+FormatFloat('#,0.000',SW.Elapsed.TotalMilliseconds));
    finally
      CoUninitialize;
    end;
 except
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Readln;
end.

Answer 1

These are some tips to improve the WMI performance

1.) Reutilize the call to CreateOleObject

2.) Reuse the WMI Connection

One of more expensive tasks is make a connection to the WMI services, so reutilize that conneciton instead of create one conneciton each time which call the function.

3.) Only retrieve the columns which you want to use

Every property which retrieve the WMI has different sources like the Windows registry, the WinAPi and so on, restricting the columns will improve the performance. read this article for more info How obtain the source of the WMI Data

4.) Use the WBEM_FLAG_FORWARD_ONLY flag when you execute the WQL sentence.

Following the above tips I rewrote your sample app

{$APPTYPE CONSOLE}

uses
  Diagnostics,
  SysUtils,
  ActiveX,
  ComObj,
  Variants;

var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;

function  GetWMIInfo(const WMIClass, WMIProperty:string): string;
const
  wbemFlagForwardOnly = $00000020;
var
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  Result:='';
  FWbemObjectSet:= FWMIService.ExecQuery(Format('Select %s from %s',[WMIProperty, WMIClass]),'WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  if oEnum.Next(1, FWbemObject, iValue) = 0 then
    Result:=FWbemObject.Properties_.Item(WMIProperty).Value;
end;

var
 SW : TStopwatch;

begin
 try
    CoInitialize(nil);
    try
      SW.Reset;
      SW.Start;
      FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
      FWMIService   := FSWbemLocator.ConnectServer('localhost', 'root\CIMV2', '', '');
      Writeln('Procesor Id '+GetWMIInfo('Win32_Processor','Name'));
      Writeln('Mother Board Serial '+GetWMIInfo('Win32_BaseBoard','SerialNumber'));
      Writeln('BIOS Version '+GetWMIInfo('Win32_BIOS','Version'));
      SW.Stop;
      Writeln('Elapsed ms '+FormatFloat('#,0.000',SW.Elapsed.TotalMilliseconds));
    finally
      CoUninitialize;
    end;
 except
    on E:EOleException do
        Writeln(Format('EOleException %s %x', [E.Message,E.ErrorCode]));
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Readln;
end.

And the execution goes from 1245 to 180 ms (on my laptop).