Problem gelöst:
Man muss noch
res.CacheLimit = DB_NONE
setzen, damit nichts gecached wird.
Aus der Hilfe:
To get: limit& = odbcResultSet.CacheLimit
To set: odbcResultSet.CacheLimit = limit&
Usage
The limit is DB_ALL (full set), DB_NONE (minimum set), or the number of rows to store. DB_NONE means that only a very small window, including the current row, is kept in memory.