Database snapshot - usage of CPU

Question

Hi,
I have a db and a snapshot for this db.
I notice that the CPU time when a query is executed on snapshot is 8 times, in my case, greater than if the same query is executed on the original db.
My question is: this behavior it's normal ? If I want to move my reports on the snapshot, the CPU used by SQL Server will increase ? 
The SQL Server has a 'maximum server memory', so, is possible that the other processes to be hampered ?
Thank you

Answer 1

Hi,
Below are some results/numbers. There wasn't any modification on the original db. No other query had been executed during the tests.
original db                                            
     snapshot
CPU time = 3150 ms,  elapsed time = 91388 ms  
   CPU time = 24742 ms,  elapsed time = 92031 ms.
CPU time = 3351 ms,  elapsed time = 65084 ms.  
  CPU time = 25164 ms,  elapsed time = 83976 ms.
CPU time = 3388 ms,  elapsed time = 85176 ms.  
  CPU time = 28545 ms,  elapsed time = 73152 ms
CPU time = 3104 ms,  elapsed time = 97374 ms.  
  CPU time = 34378 ms,  elapsed time = 89167 ms
Observation: elapsed time is the same
original
Table
 Scan count
 logical reads
 physical reads
 read-ahead reads
A
  5
  1047
  2
  946
B
  5
  11428
  1
 11310
C
  3
  1828
  3
1653
D
  1
  3
  0
  0
E
  5
  456748
  0
  456341
snapshot
Table
 Scan count
 logical reads
 physical reads
 read-ahead reads
A
  5
  954
   0
  954
B
  5
  11313
   0
  11313
C
   5
  1665
   0
  1665
D
   1
  3
   1
  3
E
   5
  456748
   0
  456748