Yes, it will impose a major concern. Bandwidth/capacity and throughput. The LAN users will see excellent performance but it is possible and very likely that users across a WAN will experience poor performance due to either the capacity of their links or the throughput which may be due to high latency if the clients are a long distance from the server. You should have all of the processing done at the server tier(s) and only the results returned to the users if possible. The client software should be as light as possible and do as very little processing as necessary to generate the needed results.