Screen takes a long time to render

Question

APEX 2.2 form with many regions displayed.
One region is a matrix of about 10 columns and, potentially, hundreds of rows constructed using the HTMLDB_ITEM.HIDDEN, HTMLDB_ITEM.TEXTAREA, HTMLDB_ITEM.SELECT_LIST_FROM_LOV, HTMLDB_ITEM.TEXT and HTMLDB_ITEM.CHECKBOX functions.
When there are few rows, the region displays very quickly. When there are 200-300 rows, the region can take 20-30 seconds to display.
Running the same SQL in SQL*Plus for a 300 row region takes less than 0.5 secs.
To try to isolate the problem I created two SQL regions, one above the below, the region taking the time.
Running
select to_char(systimestamp,'HH24:MI:SS:FF') time_mark
from dual
I got 16:05:32:007738 and 16:05:57:498557.
The whole form is just under 1MB in size (when there are 300 rows in the large region). By monitoring the Windows task manager you can see the data getting transferred to IE in one rapid spike. The browser then takes a few seconds to display the form.
Can anyone help to explain where the 20 -30 seconds is going?
It seems to me that its either APEX itself or the AS (although the AS seems to be idle mostly)
Can anyone offer any tuning suggestions?
Thanks
Adam

Answer 1

Hi Adam,
I've had similar problems before (but not in an Apex app). Whilst it may not be the same for you, the problem related to (A) the select lists and (B) the table widths.
In both, it was because the browser had to load the data and then determine how to display it. It has to work out the width of each select list and then the width of every cell to work out the width of each column and, thus, the table.
You can improve the speed by using the "table-layout:fixed" style for the table and by using COL tags with style="width:nnnpx". Together these force the browser to use specific widths for each column and stops it working out the widths for itself. If you don't want to use COL tags, the width would then be set by the width of the first row's cells. Either way, you need to adjust your report template to make these settings.
Additionally, the longer the select lists, the worse the page-load time. You can see if these are causing the problem by using popup popup LOVs instead.
Regards
Andy