在兼容级别80中运行SQL Server 2005数据库是否会对性能产生负面影响？

Our software must be able to run on SQL Server 2000 and 2005. To simplify development, we're running our SQL Server 2005 databases in compatibility level 80. However, database performance seems slower on SQL 2005 than on SQL 2000 in some cases (we have not confirmed this using benchmarks yet). Would upgrading the compatibility level to 90 improve performance on the SQL 2005 servers?Our software must be able to run on SQL Server