Console app memory leak?

Greetings,

please help me to understand why grows the used memory in this slow loop?

Var s As String
Var act As UInt64 = Runtime.MemoryUsed
Var prev As UInt64
Var delta As Int64

Do
DoEvents(3333)
s = DateTime.Now.SQLDateTime

act = Runtime.MemoryUsed
delta = act - prev
prev = act
System.DebugLog(“Mem=” + act.ToString + “, delta=” + delta.ToString)
Loop