为什么内存运行速度比硬盘运行速度快？

页面:/news/view-451220/ | 耗时:0.1897 s | 内存:1.89 MB | 查询:4 | 缓存读取:4 写入:0 | 加载文件:23
select * from tbl_Articles WHERE ArticleID=451220 LIMIT 0,1
select * from tbl_Articles_data WHERE ArticleID=451220 LIMIT 0,1
select * from tbl_Articles_sphinx where id=451220 LIMIT 0,1
SELECT ArticleID,Title FROM tbl_Articles WHERE ArticleID IN(785101,604026,2128055,2469348,1590101,408354,2666854,1091763,1984239,2553755,1083114,3169362,650481,2369218,3378377,2150270,2104594,2603043,916200,98852,673440,3506600,1746787,2493784,1209375,1205461,410684,98780,1305219,84609) ORDER BY field (ArticleID,785101,604026,2128055,2469348,1590101,408354,2666854,1091763,1984239,2553755,1083114,3169362,650481,2369218,3378377,2150270,2104594,2603043,916200,98852,673440,3506600,1746787,2493784,1209375,1205461,410684,98780,1305219,84609)