1. A method comprising: providing, by an online game system comprising at least one processor, a plurality of data files in a file directory of a file system, wherein the file directory comprises at least one subdirectory; building-up, by the online game system, a virtual file system in the online game system in a pre-processing procedure, comprising: generating encoded file system information comprising, for each data file of the plurality of data files, compressing the data file, and processing an encoded value for the compressed data file; generating a directory content file listing subdirectories of the file system; compressing the directory content file; determining an encoded value of the compressed directory content file; storing the encoded file system information and the directory content file in a central memory device accessible by a plurality of client devices; loading at least a portion of the encoded file system information and the compressed directory content file in a local memory device assigned to a client device of the plurality of client devices, reading the compressed directory content file at the client device; and performing, by the online game system, an online session in the client device, the performing comprising: receiving a request for a data file of the plurality of data files, the request comprising request information identifying the data file: determining whether the data file requested is available in the local memory device by comparing the request information to the encoded file system information and to the compressed directory content file received in the local memory device; and if it is determined that the data file is not available in the local memory device, loading the data file from the central memory device into the local memory device, the loading further comprising receiving the data file, processing a locally processed encoded value of the data file, and storing the data file and the locally processed encoded value in the local memory device.