I found a performance / Viewport update bug in my Plugin which was no bug in older C4D versions.
These two methods make the viewport slow , and message "blocks" the update till i interact with the viewport.
Tooldata - Point mode tool

# Problematic in R2026
def GetState(self, doc):
    if doc.GetMode() != c4d.Mpoints:
        c4d_progressbar(text="Go into Point Edit Mode!")
        return False
    elif len(doc.GetActiveObjects(c4d.GETACTIVEOBJECTFLAGS_0)) != 1 : 
        c4d_progressbar(text="Only one Object allowed!")
        return False
    else:
        c4d_progressbar(clear=True)
    return c4d.CMD_ENABLED

# Problematic in R2027

def Message(self, doc, parameters, type, t_data):
    if doc.GetMode() != c4d.Mpoints:
        self.FreeTool(doc, parameters)
        return False
    return True

thank you for your time
mogh