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Every time I open stackoverflow.com and click on the "questions" tab, the page doesn't update with new questions. Why?


Question: Multiple orders in a single list
Answer: There may be minor performance considerations involved with it, but this sounds like the sort of thing LINQ is very useful for. The basic idea is this:

var enormousList = new List&lt;record&gt;();

//var enormousList = ... (over 5 million records)
var subList = enormousList.Where(onerecord =&gt; onerecord.clanName == "RAGIN CAJUN");

// At this point in the program, NO filtration has occurred just yet and little processing
// power has been used.

// This enumerates the list once for the "ragin cajun" filter, so this may take a while.
var sublistCount = subList.Count(); //take note that Count is a function here, not a property. 
var pageSize = 50;
var hudDisplayPage = enormousList.Take(pageSize).Select((record, idx) =&gt;
{
    return new HudPage(idx, record.clanName, record.playerName);
});
// for those who couldn't keep track; hudDisplayPage is now an IEnumerable (which you can use for-each on) containing
// 50 records of the list fitting the description. These are dynamic constructs; even now, hudDisplayPage hasn't
// yet been evaluated. If you want to cache one of these values so you're not doing the processing again later...
var saved = hudDisplayPage.ToArray();


This sort of system should make it relatively easy to take slices out of your data, and precache whichever ones are likely to be needed many times.
Also, take note of this handy tip (but ONLY for queries that end up being a performance hit)

var saved = hudDisplayPage.AsParallel().ToArray();


That line should essentially multithread your filtration process, so that all cores of your processor are on it.

I can't say I know enough about your problem to write out its solution in code; but it seems like your issue is mainly in figuring out the list processing, against a single list you don't want to modify or copy. Hope I haven't misunderstood your issue!