SOLR4 is not relevant for your use case as the FileFolderService uses database queries for data retrieval. The list operation retrieves the children of the folder in the order they are provided by the database (not necessarily the same as the creation date) and only performs an in-memory sort. If you do not specify a specific sort order, it will use the order in which the items have been added to the folder (which also is not necessarily the same as the creation date, e.g. when an item was moved into a folder long after it was created).
As an alternative to FileFolderService.list() you can also do an FTS query against the database using the Transactional Metadata Query feature added with Alfresco 4.2. A FTS query will apply the sort condition immediately within the SQL select statement. The same also applies if you use SOLR4 for this type of query (e.g. if you request the query to use EVENTUAL consistency or your database has not been prepared for Transactional Metadata Queries).
I am completely agree with your answer.But i need to use pagination also .So for that i want alfresco to first get all result, sort the result based on sortProps and then revert the result.but it seems first alfresco getting the result based on my paging request and then performing sort then reverting.