winforms - C# Removing Dublettes from List -

i have got list changing every second. want check list, if gets big. first step delete double entries list.

there many ways accomplish this. have seen hashtables, linq , others. problem need fast way accomplish this.

there quite lot of entries in list, , user shouldn't see application freezing, if possible, because application showing animation.

i don't know, if can use hashtables, because order of objects inside of list should kept untouched, if possible.

i tried using linq , groupby, working on visual studio 2008, not contain linq statement.

the objects not simple. imagine object car. can have manufacturer, manufacturing time, model name, etc.

i want see if manufacturer , model name twice inside of list. manufacturing time not important , should ignored.

in end want delete double entries list.

i happy suggestions. if have ideas please write them down , see.

rather delete double entries when list gets big, not better not allow double entries in first place? 1 way combine collection index of sort.

the normal practice use have 2 collections - 1 data , 1 index.

list<myclass> _collection; dictionary<myclasskey, myclass> _index;

then when add, first check index , add if it's not there - otherwise don't add.

void add(myclass item) {     if (!_index.containskey[item.key])     {         _collection.add(item);         _index.add(item.key, item);     } }

this remove problem of deleting duplicates later , therefore no ui slowdown.

obviously code above not thread safe - it's illustrate point.

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