thank you Dragan.i look at this download nextly.

after making some tests previous night, there is indeed a pc performances.i tested only on local PC .
i watched the task manager and the memory occupation.
At this time i choose this solution:
1.make a standalone exe working with scheduler (1 once by day-to adapt).this is focused only on building/re building the table of all PC files (all discs).
this makes nearly 10 minutes to build this table of 700.000 files in my workstation.

2.make another standalone exe for search exclusively. it uses a cursor built from the previous table and make asynchronous search (nearly of synchrone search if mother table is updated frequently).
this works as well if the first exe is not running otherwise it fires vfp progressbars and becomes slighly slow only at starting.

3.of course user can run first exe independent of windows scheduler as option.

this solution is decent and any search is " like instantaneous" one