Two chart does not plot at same time while some delay occur

What MCU/Processor/Board and compiler are you using?
stm32h743ii, stm32cubeide, gcc

What LVGL version are you using?
v 7

What do you want to achieve?
Two chart update same time and does not lag

Code to reproduce

lv_obj_t *cont = lv_cont_create(lv_scr_act(), NULL);
lv_obj_set_size(cont, 600, 420);
lv_obj_set_pos(cont, 200, 60);
lv_obj_set_style_local_bg_color(cont, LV_OBJ_PART_MAIN, LV_STATE_DEFAULT,LV_COLOR_BLACK);
lv_obj_set_style_local_border_width(cont, LV_OBJ_PART_MAIN, LV_STATE_DEFAULT,0);

pchart = lv_chart_create(cont, NULL);
lv_obj_set_size(pchart, 580, 150 );
lv_obj_set_pos(pchart, 10, 30 );
lv_chart_set_type(pchart, LV_CHART_TYPE_LINE);
lv_chart_set_update_mode(pchart, LV_CHART_UPDATE_MODE_CIRCULAR);
pseries = lv_chart_add_series(pchart, vl_graph_clr);
lv_chart_set_point_count(pchart, 100);
lv_obj_set_style_local_bg_color(pchart, LV_OBJ_PART_MAIN, LV_STATE_DEFAULT,RECTANGLE_OUTLINE);

vchart = lv_chart_create(cont, NULL);
lv_obj_set_size(vchart, 580, 150 );
lv_obj_set_pos(vchart, 10, 250 );
lv_chart_set_type(vchart, LV_CHART_TYPE_LINE);
lv_chart_set_update_mode(vchart, LV_CHART_UPDATE_MODE_CIRCULAR);
vseries = lv_chart_add_series(vchart, vl_graph_clr);
lv_chart_set_point_count(vchart, 100);
lv_obj_set_style_local_bg_color(vchart, LV_OBJ_PART_MAIN, LV_STATE_DEFAULT,RECTANGLE_OUTLINE);

//while loop given every 20ms once
lv_chart_set_next(vchart, vseries,adc_graph_data);
lv_chart_set_next(pchart, pseries,adc_graph_data);

Two chart plot at same update

After 2min one chart and another chart plot some delay occur (chart data lag)

After 2min one chart and another chart plot some delay occur (chart data lag).Initial two chart plot same time. After 2min some lag occur in two chart

Does the delay stay constant or it gets more and more?
I had a rather similar problem some time ago.
It was solved by increasing ‘LV_INV_BUF_SIZE’ to 256. so then it prevents the whole screen refresh and the lag on chart refresh.
Not sure, but hope this can help.

Thanks. Now added chart refresh function it solve the problem.