public static PageData GetPageList(int pageSize, int curPage,Mer m)
{

//m ：当前登录的用户

List<ComOrder> o = DataAccess.GetAllList();//
List<ComOrder> n = new List<ComOrder>();//分中心数据
List<ComOrder> nn = new List<ComOrder>();//用户数据

if (m.MerType.Data == "分中心")
{
foreach (ComOrder c in o)
{
if ( m.Merchants.Contains(c.Subcenter))
{
n.Add(c);
}
}
}
else
{
foreach (ComOrder c in o)
{
if (c.JoiningTrader.Id == m.Id)
{
n.Add(c);
}
}

}

PageData pageData = new PageData();
pageData.PageSize = pageSize;
pageData.CurPage = curPage;
pageData.RecordCount = 0;
pageData.PageCount = 1;

int first = (curPage - 1) * pageSize + 1;
int last = curPage * pageSize;

foreach (ComOrder c in n)
{
pageData.RecordCount++;
if (pageData.RecordCount >= first && last >= pageData.RecordCount)
{
ComOrder comOrder = c;

nn.Add(comOrder);
}
}

if (pageData.RecordCount > 0)
pageData.PageCount = Convert.ToInt32(Math.Ceiling((double)pageData.RecordCount / (double)pageSize));

pageData.PageList = nn;
return pageData;
}

这样效率很慢  我能想明白问题  但是优化的时候越想越头疼，麻烦大神了