Under Windows, performance counters have different names, depending on the operating system language. For example, on an English Windows version, there is the performance counter \Processor(_Total)\% Processor Time. The same counter is called \Prozessor(_Total)\Prozessorzeit (%) on a German Windows version.
Is there any way to retrieve the performance counter value in a language-independent way (using C++ or C#)? Or is there an alternative to get the processor load of the whole computer without performance counters?
Each PerfMon counter is given a unique (per machine) integer ID to identify the PerfMon counter (however in the case of the standard counters this id is guaranteed to stay the same).
The information linking PerfMon counters id's to both their US English name and their Localized name is stored in the registry in the following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Perflib
Once you have used the registry to obtain the PerfMon counter name (which you can embed in your app as a constant for standard counters) you can use the PdhLookupPerfNameByIndex function to look up the localized name for the given counter ID.
See Using PDH APIs correctly in a localized language (Microsoft KB) for more details.
You might also find Finding perfmon counter id via winreg (StackOverflow) somewhat relevant.