Some spikes would be expected as accessing the file system and packaging for transfer over the network will use up resources and it is beremote.exe that is responsible for this process. Kind of depends on what you mean by 'spikes' and whether or not it holds at that level for an extended period of time or does not return the memory when the job completes.
If you are comparing the memory after restarting the Backup Exec Remote Agent Service with that after 1 Job has finished then I think it does use a little more as some modules are cached the first time a backup runs - what you should find is if you compare the memory after the first run of a backup with after a second run (where you have NOT restarted the services) that it should be close to the same - although if you run a different type of backup then another module might be called so it may still vary a little depending on what you do - i.e. if SQL and Exchange are on same server and you run an Exchange backup, the exchange libraries will be loaded if you then run a SQL backup it will load the SQL libraries and leave the Exchnage ones loaded too.
