APEX

I'm tasked with developing a primarily client side application in Apex. I have very rigid requirements that do not seem to adapt well to Apex.
I'm using Apex 19.1
Nearly all the code is done in javascript due to the client side requirement. Doing these in pl/sql caused a noticeable lag that was undesirable.
I have approximately 500 page items on the global page that are used to carry values from page to page. These are initialized via an Ajax Callback when the user selects the account they want to work on. These values are used to recalculate pages.
On the first page the user enters a value in item 1 and item 2 and item 3 is calculated from the data entered.
Then all the pages are recalculated using javascript calculations that read the values in the global page items. The items for all pages are then set to submit and set in session state using the apex item method. The values are saved to a table in the database in a submit process.
The user then chooses another page to continue data entry. When the user goes to the new page, the values from the first page are in session state. In pl/sql on page load I can view the values. However, when I try to access the value using javascript, the value is reset.
This has been a chronic intermittent problem that I've isolated but can not explain and therefore can't correct without reloading the page values from the database. Doing this again causes a noticeable lag that is undesireable. It's my understanding that it shouldn't be necessary to reload the values since they are on the global page.
Any ideas are welcome...but please refrain from telling me to take a different approach completely. I've approached this from several different angles. The previous solution was done in jsp using notepad and works fine, but a nicer looking interface was desired.