Do you do pagination database side?

Pagination can be expensive if all the pages are retrieved from the database before grabbing the relevant page. It's much more efficient to get only the page number requested back from the database.

var query = context
    .Sales
    .AsNoTracking()
    .Where(x => x.SalesPersonId == salesPersonId);
var result = await query.ToListAsync();
int count = result.Count;

result = result
    .Skip(page * pageSize)
    .Take(pageSize);
return (count, result);

var query = context
    .Sales
    .AsNoTracking()
    .Where(x => x.SalesPersonId == salesPersonId);

int count = await query.CountAsync();

query = query
    .Skip(page * pageSize)
    .Take(pageSize);
var result = await query.ToListAsync();    
return (count, result);