SPQuery query = new SPQuery();
string view = "<FieldRef Name='Title'/><FieldRef Name='Field1'/><FieldRef Name='Field2'/>"

query.ViewFields = view;
query.ViewFieldsOnly = true;

query.IncludePermissions = false;
query.RowLimit = rowLimitNumber; //for example 1000
query.IncludeAllUserPermissions = false;
query.IncludeAttachmentUrls = false;
query.IncludeAttachmentVersion = false;
query.IncludeMandatoryColumns = false;
query.RecurrenceOrderBy = false;

query.Query = queryString;