Set the size while restore
MAXTRANSFERSIZE
Specifies the maximum size of each block of memory to be used when SQL Backup stores backup data. You may want to specify this argument if a SQL Server reports that it has insufficient memory to service requests from SQL Backup.
Valid values are integers in multiples of 65536, up to a maximum value of 1048576.
For example:
MAXTRANSFERSIZE = 262144
If not specified, defaults to 1048576. However, if you have created the following DWORD registry key, SQL Backup uses the defined value as the default value:
HKEY_LOCAL_MACHINE\SOFTWARE\Red Gate\SQL Backup\BackupSettingsGlobal\<instance name>\MAXTRANSFERSIZE (32-bit)
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Red Gate\SQL Backup\BackupSettingsGlobal\<instance name>\MAXTRANSFERSIZE (64-bit)