c# - C # memory management and performance -

the criteria simple. developing winform application using c# 4.0 , have win form having grid view. on load event, retrieve data database , assign datasource gridview. have used backgroundworker object database retrieval. nice. gui responsive. records more 10 lac. fill datatable using background worker , assign datatable gridview. problem is, system gets slower. when minimize mdi form of application , try other things opening internet browser , stuff, pc gets slower. have core i3 2ith 2gb ram. grid having 10 lac records makes system slow. how manage memory in case? here code:

backgroundworker bworker; datatable dt;

    public form1()     {         initializecomponent();         bworker = new backgroundworker();         bworker.dowork += new doworkeventhandler(m_oworker_dowork);         bworker.progresschanged += new progresschangedeventhandler(m_oworker_progresschanged);         bworker.runworkercompleted += new runworkercompletedeventhandler(m_oworker_runworkercompleted);         bworker.workerreportsprogress = true;         bworker.workersupportscancellation = true;     }      void m_oworker_runworkercompleted(object sender, runworkercompletedeventargs e)     {         datagridview1.datasource = dt;         picturebox1.visible = false;         //progressbar1.style = progressbarstyle.blocks;         //label1.text  = "data loaded successfully!";         this.hide();         this.show();     }      void m_oworker_dowork(object sender, doworkeventargs e)     {         dt = getdatatable();         //bworker.reportprogress(100);     }     void m_oworker_progresschanged(object sender, progresschangedeventargs e)     {         //here play main ui thread         //progressbar1.value = e.progresspercentage;     }      private void form1_load(object sender, eventargs e)     {         bworker.runworkerasync();      }     private datatable getdatatable()     {         string constr = constring;         sqlconnection con = new sqlconnection(constr);         sqlcommand cmd = new sqlcommand("select *from testtable",con);         sqldataadapter da = new sqldataadapter(cmd);         dt = new datatable();         try         {             da.fill(dt);             return dt;         }         catch (exception ex)         {             messagebox.show(ex.tostring());             return null;         }     } 

please guide me how manage memory system should not slower. if dispose datatable after assigning grid, help?

i beginner. , want complete guidance memory management. application should fast. thanx

most problem datagridview creates row each row in result set. should read virtual display mode is, virtualmode property , how implement it.