HTTP2 vs HTTP1 Performance

Testing HTTP 1.1 

The test is very simple, just call server to get an image 100 times, one by one, so when first finishes, second request is sent and so on

procedure TestHTTP1;
begin
  oHTTP := TIdHTTP.Create(nil);
  Try
    for i := 1 to 100 do
    begin
      oStream := TMemoryStream.Create;
      Try
        oHTTP.Get('https://ik.imagekit.io/demo/img/http_test/h_' + Format('%.2d', [i]) + '.jpg', oStream);
        oJPEG := TJPEGImage.Create;
        oJPEG.Scale := jsHalf;
        oStream.Position := 0;
        oJPEG.LoadFromStream(oStream);
        ...
        TThread.Queue(nil,
        procedure
        begin
          FRMHTTP2_Client.imgHTTP.Canvas.Draw(vCol * 50, vRow * 50, oJPEG);
        end);
      Finally
        oStream.Free;
      End;
    end;
  Finally
    oHTTP.Free;
    Terminate;
  end;      
end;   

Testing HTTP 2.0

The test is still more simple than with HTTP 1.1, just create http2 component, and call 100 times to get request, there is no need to wait to get a response because responses are dispatched asynchronously when are received by client. 

procedure TestHTTP2;
var
  oHTTP2: TsgcHTTP2Client;
begin
  oHTTP2 := TsgcHTTP2Client.Create;
  oHTTP2.OnHTTP2Response := OnHTTP2ResponseEvent;
  oHTTP2.Request.Accept := 'image/*,*/*;q=0.8';
  for i := 1 to 100 do
    oHTTP2.Get('https://ik.imagekit.io/demo/img/http_test/h_' + Format('%.2d', [i]) + '.jpg');
end;

procedure OnHTTP2ResponseEvent(const Connection: TsgcHTTP2ConnectionClient; const Request: TsgcHTTP2RequestProperty; const Response: TsgcHTTP2ResponseProperty);
var
  oJPEG: TJPEGImage;
  vCol, vRow: Integer;
begin
  oJPEG := TJPEGImage.Create;
  oJPEG.LoadFromStream(Response.Data);
  oJPEG.Scale := jsHalf;
  ...
  TThread.Queue(nil,
  procedure
  begin
    if Assigned(imgHTTP2) then
    begin
      imgHTTP2.Canvas.Draw(vCol * 50, vRow * 50, oJPEG);
    end;
  end);
end;   

And the winner is...

Most probably you already know which protocol is faster, you can test yourself using the following compiled demo for windows. 

NOTE: in the demo, the HTTP1.1 test runs in a secondary thread and HTTP2.0 is asynchronous so it doesn't needs to run in a secondary thread.