Ondea "Because the integer unit and FPU are separate execution units, it is possible for the processor to execute floating-point, integer, and system instructions concurrently. No special programming techniques are required to gain the advantages of concurrent execution. (Floating-point instructions are placed in the instruction stream along with the integer and system instructions.) However, concurrent execution can cause problems for floating-point exception handlers. This problem is related to the way the FPU signals the existence of unmasked floating-point exceptions. (Special exception synchronization is not required for masked floating-point exceptions, because the FPU always returns a masked result to the destination operand.) When a floating-point exception is unmasked and the exception condition occurs, the FPU stops further execution of the floating-point instruction and signals the exception event. On the next occurrence of a floating-point instruction or a WAIT/FWAIT instruction in the instruction stream, the processor checks the ES flag in the FPU status word for pending floating-point exceptions. It floating-point exceptions are pending, the FPU makes an implicit call (traps) to the floating-point software exception handler. The exception handler can then execute recovery procedures for selected or all floating-point exceptions. Synchronization problems occur in the time frame between when the exception is signaled and when it is actually handled. Because of concurrent execution, integer or system instructions can be executed during this time frame. It is thus possible for the source or destination operands for a floating-point instruction that faulted to be overwritten in memory, making it impossible for the exception handler to analyze or recover from the exception. To solve this problem, an exception synchronizing instruction (either a floating-point instruction or a WAIT/FWAIT instruction) can be placed immediately after any floating-point instruction that might present a situation where state information pertaining to a floating-point exception might be lost or corrupted. Floating-point instructions that store data in memory are prime candidates for synchronization." (quote from Intel Architecture Software Developers' Manual, Volume 1: Basic Architecture, Chapter 7.9 "Floating-point exception synchronization"). The Delphi compiler puts FWait instructions after every statement that uses floating-point data. This helps trapping errors during debugging, but (almost) needlessly slows down execution of final releases.  Ondea is tool that parses EXE files for FWait opcodes ($9B) and replaces them with Nop opcodes ($90). No debugging info is needed. Click here for the User Guide. Please note that  removing FWait opcodes will give a speed-boost that depends on the amount of floating-point computations performed; exception handlers may get fooled: if the last FP instruction in a code block raises an FP exception, it will not be reported until the next FP instruction, that may belong to a different code block, gets executed! the processed EXE file may not work correctly! Please do not send me e-mail such as "I've tried Ondea on my X exe file, and now it does not work correctly, why?", I'm not going to browse through tons of assembly codes to find what gone wrong! If it works, fine; if it does not, just forget about it! THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Click here to download Ondea (197 KB)! Credits: the PE executable file format info is extracted using parts of the PE Information module of the GExperts 0.97.1 by Gerald Nunn and others (http://www.gexperts.com).