Custom move element tool is not fast as the built-in Microstation "Move extended" when hundreds of elements are manipulated[V8i MDL]

Hello! It´s me again, with a question.

I´m currently working with a Microstation V8i SS4 version, where I needed to add my own functionality to the move tool, so I´ve decided that I will implement myself it with MDL API, as VBA didn´t offer me the things I wanted (and the tool didn´t have that "native microstation tool" feeling). It was also a great opportunity to learn new things.

Functionality is working properly. Everything was great until I have decided to add support of selection set for my tool. Now I was facing a problem with performance, where for example I move around like 500+ elements (of all kinds) and I can see that the FPS is dropped (so the movement is not that smooth). I´ve tried to do the same thing with the "move extended" keyin (I simply launched it from my C++ code) and the performance was much better, smoother, as the number of elements selected didn´t affect it at all.

Now to the implementation (as the code is quite complex I won´t share it all):

Depending on whether user uses selection set or no, I start Modify command
    if (mdlSelect_numSelected() > 0)
    {
        mdlState_startModifyCommand(NULL, acceptFunc, updateFunc, NULL, NULL, 0, 0, TRUE, 2);       
    }
    else
    {
        mdlState_startModifyCommand(NULL, acceptFunc, updateFunc, NULL, NULL, 0, 0, FALSE, 0);
    }
    
Then I set some mdlLocate settings like enabling accusnap etc. (as I think it does not affect
the perfomance, I will skip that)

From the selected elements, I iterate through them, receive ElementRef and create transient elements (the copies that you see moving around with mouse)

    MSElementDescr* descr = nullptr;
    ElementRef descrRef = elementRef_getParent(ref);
    if (descrRef == NULL)
    {
        descrRef = ref;
    }

    mdlElmdscr_getByElemRef(&descr, descrRef, mdlModelRef_getActive(), 0, 0);
    TransDescrP createdTrans = mdlTransient_addElemDescr(NULL, descr, FALSE, 0x00ff, DRAW_MODE_TempDraw, FALSE, FALSE, FALSE);
    _transDescriptors.emplace_back(createdTrans);
    
Then in the dynamic update function, I move them according to the movements of my mouse

for(int i = 0; i < _transDescriptors.size(); i++)
    {
        MSElementDescr* descr;
        mdlTransient_returnElemDescr(&descr, _transDescriptors[i]);

        Transform transformMatrix;
        mdlTMatrix_getIdentity(&transformMatrix);
        mdlTMatrix_setTranslation(&transformMatrix, &mousePoint);
        mdlElmdscr_transform(descr, &transformMatrix);     
        
        _transDescriptors[i] = mdlTransient_replaceElemDescr(_transDescriptors[i], _copyDescriptors[i], FALSE, 0x00ff, DRAW_MODE_TempDraw, FALSE, TRUE, TRUE);
    }

Thats my main approach, but I also tried a different one, but with same results:

Instead of iterating through all elements, I added them to a temporary created cell (using mdlElmdscr_append).

Then i simply just translated this single element, however it didn´t improve the performance, or run smoother.

Do you guys have some ideas what could cause my problems? Is there some workaround to speed up described behavior? Thanks in advance.